diff --git a/src/alsa_card.rs b/src/alsa_card.rs
index 1ab2bef46..ee8f669f7 100644
--- a/src/alsa_card.rs
+++ b/src/alsa_card.rs
@@ -1,3 +1,5 @@
+#![allow(illegal_floating_point_literal_pattern)]
+
 //! Alsa audio subsystem.
 //!
 //! This mod mainly defines the `AlsaCard` struct, which is the only data
@@ -10,17 +12,21 @@ use alsa::mixer::SelemChannelId::*;
 use alsa::mixer::{Mixer, Selem, SelemId};
 use alsa::poll::PollDescriptors;
 use alsa_sys;
+use audio::*;
 use errors::*;
+use glib;
 use glib_sys;
 use libc::c_uint;
 use libc::pollfd;
 use libc::size_t;
 use std::cell::Cell;
+use std::cell::RefCell;
 use std::mem;
 use std::ptr;
 use std::rc::Rc;
 use std::u8;
 use support_alsa::*;
+use support_audio::*;
 
 
 
@@ -67,8 +73,6 @@ impl AlsaCard {
     /// If an elem name is provided, it will be tried. If `None` is provided
     /// or the given elem name does not exist or is not playable, any other
     /// playable elem is tried.
-    /// ## `cb`
-    /// Callback for the various `AlsaEvent`s.
     ///
     /// # Returns
     ///
@@ -122,11 +126,11 @@ impl AlsaCard {
 
         let acard = Box::new(AlsaCard {
                                  _cannot_construct: (),
-                                 card: card,
-                                 mixer: mixer,
-                                 selem_id: selem_id,
+                                 card,
+                                 mixer,
+                                 selem_id,
                                  watch_ids: Cell::new(vec![]),
-                                 cb: cb,
+                                 cb,
                              });
 
         let watch_ids = AlsaCard::watch_poll_descriptors(vec_pollfd,
@@ -136,89 +140,13 @@ impl AlsaCard {
         return Ok(acard);
     }
 
-
-    /// Get the name of the alsa card.
-    pub fn card_name(&self) -> Result<String> {
-        return self.card.get_name().from_err();
-    }
-
-
-    /// Get the name of the channel.
-    pub fn chan_name(&self) -> Result<String> {
-        let n = self.selem_id
-            .get_name()
-            .map(|y| String::from(y))?;
-        return Ok(n);
-    }
-
-
     /// Get the `Selem`, looked up by the `SelemId`.
-    pub fn selem(&self) -> Selem {
-        return self.mixer.find_selem(&self.selem_id).unwrap();
+    fn selem(&self) -> Selem {
+        let selem_id = &self.selem_id;
+        let selem = self.mixer.find_selem(selem_id);
+        return selem.unwrap();
     }
 
-
-    /// Get the current volume. The returned value corresponds to the
-    /// volume range and might need to be interpreted (such as converting
-    /// to percentage). This always gets
-    /// the volume of the `FrontRight` channel, because the seems to be
-    /// the safest bet.
-    pub fn get_vol(&self) -> Result<i64> {
-        let selem = self.selem();
-        let volume = selem.get_playback_volume(FrontRight);
-
-        return volume.from_err();
-    }
-
-
-    /// Sets the volume of the current card configuration.
-    /// ## `new_vol`
-    /// The volume corresponding to the volume range of the `Selem`. This
-    /// might need to be translated properly first from other formats
-    /// (like percentage).
-    pub fn set_vol(&self, new_vol: i64) -> Result<()> {
-        let selem = self.selem();
-        return selem.set_playback_volume_all(new_vol).from_err();
-    }
-
-
-    /// Gets the volume range of the currently selected card configuration.
-    ///
-    /// # Returns
-    ///
-    /// `(min, max)`
-    pub fn get_volume_range(&self) -> (i64, i64) {
-        let selem = self.selem();
-        return selem.get_playback_volume_range();
-    }
-
-
-    /// Whether the current card configuration can be muted.
-    pub fn has_mute(&self) -> bool {
-        let selem = self.selem();
-        return selem.has_playback_switch();
-    }
-
-
-    /// Get the mute state of the current card configuration.
-    pub fn get_mute(&self) -> Result<bool> {
-        let selem = self.selem();
-        let val = selem.get_playback_switch(FrontRight)?;
-        return Ok(val == 0);
-    }
-
-
-    /// Set the mute state of the current card configuration.
-    /// ## `mute`
-    /// Passing `true` here means the card will be muted.
-    pub fn set_mute(&self, mute: bool) -> Result<()> {
-        let selem = self.selem();
-        /* true -> mute, false -> unmute */
-        let _ = selem.set_playback_switch_all(!mute as i32)?;
-        return Ok(());
-    }
-
-
     /// Watch the given alsa card poll descriptors and
     /// return the corresponding watch IDs for saving
     /// in the `AlsaCard` struct.
@@ -248,7 +176,6 @@ impl AlsaCard {
         return watch_ids;
     }
 
-
     /// Unwatch the given poll descriptors.
     fn unwatch_poll_descriptors(watch_ids: &Vec<u32>) {
         for watch_id in watch_ids {
@@ -269,6 +196,269 @@ impl Drop for AlsaCard {
 }
 
 
+/// Alsa implementation of the `AudioFrontend`.
+pub struct AlsaBackend {
+    _cannot_construct: (),
+    /// The alsa card.
+    pub acard: RefCell<Box<AlsaCard>>,
+    /// Last timestamp of an internal action we triggered, e.g.
+    /// by setting the volume or the mute state.
+    pub last_action_timestamp: Rc<RefCell<i64>>,
+    /// A set of handlers that react to audio signals. We can
+    /// connect to these.
+    pub handlers: Handlers,
+    /// The step at which to increase/decrease the volume.
+    /// This value is basically from the preferences.
+    pub scroll_step: Cell<u32>,
+}
+
+
+impl AlsaBackend {
+    /// Creates the `AlsaBackend`, containing an `AlsaCard`
+    /// and additional information.
+    pub fn new(card_name: Option<String>,
+               elem_name: Option<String>)
+               -> Result<AlsaBackend> {
+
+
+        let last_action_timestamp = Rc::new(RefCell::new(0));
+        let handlers = Handlers::new();
+
+        let cb = {
+            let myhandler = handlers.clone();
+            let ts = last_action_timestamp.clone();
+            Rc::new(move |event| {
+                        on_alsa_event(&mut *ts.borrow_mut(),
+                                      &myhandler.borrow(),
+                                      event)
+                    })
+        };
+
+        let acard = AlsaCard::new(card_name, elem_name, cb);
+
+        if acard.is_err() {
+            invoke_handlers(&handlers.borrow(),
+                            AudioSignal::NoCard,
+                            AudioUser::Unknown);
+        } else {
+            invoke_handlers(&handlers.borrow(),
+                            AudioSignal::CardInitialized,
+                            AudioUser::Unknown);
+        }
+
+        let alsa_backend = AlsaBackend {
+            _cannot_construct: (),
+            acard: RefCell::new(acard?),
+            last_action_timestamp: last_action_timestamp.clone(),
+            handlers,
+            scroll_step: Cell::new(5),
+        };
+
+        return Ok(alsa_backend);
+    }
+
+
+    /// Gets the volume range of the currently selected card configuration.
+    ///
+    /// # Returns
+    ///
+    /// `(min, max)`
+    fn get_volume_range(&self) -> (i64, i64) {
+        let acard = self.acard.borrow();
+        let selem = acard.selem();
+        return selem.get_playback_volume_range();
+    }
+}
+
+
+impl AudioFrontend for AlsaBackend {
+    fn switch_card(&self,
+                   card_name: Option<String>,
+                   elem_name: Option<String>,
+                   user: AudioUser)
+                   -> Result<()> {
+        debug!("Switching cards");
+        debug!("Old card name: {}", self.card_name().unwrap());
+        debug!("Old chan name: {}", self.chan_name().unwrap());
+        let cb = self.acard
+            .borrow()
+            .cb
+            .clone();
+
+        {
+            let mut ac = self.acard.borrow_mut();
+            *ac = AlsaCard::new(card_name, elem_name, cb)?;
+        }
+
+        invoke_handlers(&self.handlers.borrow(),
+                        AudioSignal::CardInitialized,
+                        user);
+
+        return Ok(());
+    }
+
+    fn card_name(&self) -> Result<String> {
+        return self.acard
+                   .borrow()
+                   .card
+                   .get_name()
+                   .from_err();
+    }
+
+    fn chan_name(&self) -> Result<String> {
+        let n = self.acard
+            .borrow()
+            .selem_id
+            .get_name()
+            .map(|y| String::from(y))?;
+        return Ok(n);
+    }
+
+    fn playable_chan_names(&self) -> Vec<String> {
+        return get_playable_selem_names(&self.acard.borrow().mixer);
+    }
+
+    fn get_vol(&self) -> Result<f64> {
+        let acard = self.acard.borrow();
+        let selem = acard.selem();
+        let volume = selem.get_playback_volume(FrontRight)?;
+
+        return vol_to_percent(volume, self.get_volume_range());
+    }
+
+    fn set_vol(&self,
+               new_vol: f64,
+               user: AudioUser,
+               dir: VolDir,
+               auto_unmute: bool)
+               -> Result<()> {
+
+        {
+            let mut rc = self.last_action_timestamp.borrow_mut();
+            *rc = glib::get_monotonic_time();
+        }
+
+        let alsa_vol = percent_to_vol(new_vol, self.get_volume_range(), dir)?;
+
+        /* only invoke handlers etc. if volume did actually change */
+        {
+            let old_alsa_vol =
+                percent_to_vol(self.get_vol()?, self.get_volume_range(), dir)?;
+
+            if old_alsa_vol == alsa_vol {
+                return Ok(());
+            }
+        }
+
+        /* auto-unmute */
+        if auto_unmute && self.has_mute() && self.get_mute()? {
+            self.set_mute(false, user)?;
+        }
+
+        debug!("Setting vol on card {:?} and chan {:?} to {:?} by user {:?}",
+               self.card_name().unwrap(),
+               self.chan_name().unwrap(),
+               new_vol,
+               user);
+
+
+        self.acard
+            .borrow()
+            .selem()
+            .set_playback_volume_all(alsa_vol)?;
+
+        invoke_handlers(&self.handlers.borrow(),
+                        AudioSignal::ValuesChanged,
+                        user);
+        return Ok(());
+
+    }
+
+    fn vol_level(&self) -> VolLevel {
+        let muted = self.get_mute().unwrap_or(false);
+        if muted {
+            return VolLevel::Muted;
+        }
+        let cur_vol = try_r!(self.get_vol(), VolLevel::Muted);
+        match cur_vol {
+            0. => return VolLevel::Off,
+            0.0...33.0 => return VolLevel::Low,
+            0.0...66.0 => return VolLevel::Medium,
+            0.0...100.0 => return VolLevel::High,
+            _ => return VolLevel::Off,
+        }
+    }
+
+    fn increase_vol(&self, user: AudioUser, auto_unmute: bool) -> Result<()> {
+        let old_vol = self.get_vol()?;
+        let new_vol = old_vol + (self.scroll_step.get() as f64);
+
+        return self.set_vol(new_vol, user, VolDir::Up, auto_unmute);
+    }
+
+    fn decrease_vol(&self, user: AudioUser, auto_unmute: bool) -> Result<()> {
+        let old_vol = self.get_vol()?;
+        let new_vol = old_vol - (self.scroll_step.get() as f64);
+
+        return self.set_vol(new_vol, user, VolDir::Down, auto_unmute);
+    }
+
+    fn has_mute(&self) -> bool {
+        let acard = self.acard.borrow();
+        let selem = acard.selem();
+        return selem.has_playback_switch();
+    }
+
+    fn get_mute(&self) -> Result<bool> {
+        let acard = self.acard.borrow();
+        let selem = acard.selem();
+        let val = selem.get_playback_switch(FrontRight)?;
+        return Ok(val == 0);
+    }
+
+    fn set_mute(&self, mute: bool, user: AudioUser) -> Result<()> {
+        let mut rc = self.last_action_timestamp.borrow_mut();
+        *rc = glib::get_monotonic_time();
+
+        debug!("Setting mute to {} on card {:?} and chan {:?} by user {:?}",
+               mute,
+               self.card_name().unwrap(),
+               self.chan_name().unwrap(),
+               user);
+
+        let acard = self.acard.borrow();
+        let selem = acard.selem();
+        /* true -> mute, false -> unmute */
+        let _ = selem.set_playback_switch_all(!mute as i32)?;
+
+        invoke_handlers(&self.handlers.borrow(),
+                        AudioSignal::ValuesChanged,
+                        user);
+        return Ok(());
+    }
+
+    fn toggle_mute(&self, user: AudioUser) -> Result<()> {
+        let muted = self.get_mute()?;
+        return self.set_mute(!muted, user);
+    }
+
+    fn connect_handler(&self, cb: Box<Fn(AudioSignal, AudioUser)>) {
+        self.handlers.add_handler(cb);
+    }
+
+    fn set_scroll_step(&self, scroll_step: u32) {
+        self.scroll_step.set(scroll_step);
+    }
+
+    fn get_scroll_step(&self) -> u32 {
+        return self.scroll_step.get();
+    }
+}
+
+
+
+
+
 /// The C callback function registered in `watch_poll_descriptors()`.
 extern "C" fn watch_cb(chan: *mut glib_sys::GIOChannel,
                        cond: glib_sys::GIOCondition,
@@ -323,3 +513,61 @@ extern "C" fn watch_cb(chan: *mut glib_sys::GIOChannel,
 
     return true as glib_sys::gboolean;
 }
+
+
+/// Invokes the registered handlers.
+fn invoke_handlers(handlers: &Vec<Box<Fn(AudioSignal, AudioUser)>>,
+                   signal: AudioSignal,
+                   user: AudioUser) {
+    debug!("Invoking handlers for signal {:?} by user {:?}",
+           signal,
+           user);
+    if handlers.is_empty() {
+        debug!("No handler found");
+    } else {
+        debug!("Executing handlers")
+    }
+    for handler in handlers {
+        let unboxed = handler.as_ref();
+        unboxed(signal, user);
+    }
+}
+
+
+/// The callback for alsa events that is passed to the alsa subsystem.
+/// This is the bridge between low-level alsa events and "high-level"
+/// audio system signals.
+fn on_alsa_event(last_action_timestamp: &mut i64,
+                 handlers: &Vec<Box<Fn(AudioSignal, AudioUser)>>,
+                 alsa_event: AlsaEvent) {
+    let last: i64 = *last_action_timestamp;
+
+    if last != 0 {
+        let now: i64 = glib::get_monotonic_time();
+        let delay: i64 = now - last;
+        if delay < 1000000 {
+            return;
+        }
+        debug!("Discarding last time stamp, too old");
+        *last_action_timestamp = 0;
+    }
+
+    /* external change */
+    match alsa_event {
+        AlsaEvent::AlsaCardError => {
+            invoke_handlers(handlers,
+                            self::AudioSignal::CardError,
+                            self::AudioUser::Unknown);
+        }
+        AlsaEvent::AlsaCardDiconnected => {
+            invoke_handlers(handlers,
+                            self::AudioSignal::CardDisconnected,
+                            self::AudioUser::Unknown);
+        }
+        AlsaEvent::AlsaCardValuesChanged => {
+            invoke_handlers(handlers,
+                            self::AudioSignal::ValuesChanged,
+                            self::AudioUser::Unknown);
+        }
+    }
+}
diff --git a/src/app_state.rs b/src/app_state.rs
index 21a427537..80c87cb00 100644
--- a/src/app_state.rs
+++ b/src/app_state.rs
@@ -1,7 +1,8 @@
 //! Global application state.
 
 
-use audio::{Audio, AudioUser};
+use alsa_card::*;
+use audio::*;
 use errors::*;
 use gtk;
 use hotkeys::Hotkeys;
@@ -18,12 +19,14 @@ use notif::*;
 
 // TODO: destructors
 /// The global application state struct.
-pub struct AppS {
+pub struct AppS<T>
+    where T: AudioFrontend
+{
     _cant_construct: (),
     /// Mostly static GUI state.
     pub gui: Gui,
     /// Audio state.
-    pub audio: Rc<Audio>,
+    pub audio: Rc<T>,
     /// Preferences state.
     pub prefs: RefCell<Prefs>,
     #[cfg(feature = "notify")]
@@ -31,39 +34,50 @@ pub struct AppS {
     /// is set to `None`.
     pub notif: Option<Notif>,
     /// Hotkey state.
-    pub hotkeys: RefCell<Box<Hotkeys>>, // Gets an Rc to Audio.
+    pub hotkeys: RefCell<Box<Hotkeys<T>>>, // Gets an Rc to Audio.
 }
 
 
-impl AppS {
+/// Create a new application state using the `AlsaBackend`.
+pub fn new_alsa_appstate() -> AppS<AlsaBackend> {
+    let prefs = RefCell::new(unwrap_error!(Prefs::new(), None));
+
+    let card_name = prefs.borrow()
+        .device_prefs
+        .card
+        .clone();
+    let chan_name = prefs.borrow()
+        .device_prefs
+        .channel
+        .clone();
+    let audio = Rc::new(unwrap_error!(AlsaBackend::new(Some(card_name),
+                                                       Some(chan_name)),
+                                      None));
+    return AppS::new(prefs, audio);
+}
+
+
+impl<T> AppS<T>
+    where T: AudioFrontend
+{
     /// Create an application state instance. There should really only be one.
-    pub fn new() -> AppS {
+    pub fn new(prefs: RefCell<Prefs>, audio: Rc<T>) -> Self {
         let builder_popup_window =
             gtk::Builder::new_from_string(include_str!(concat!(env!("CARGO_MANIFEST_DIR"),
                                                                "/data/ui/popup-window.glade")));
         let builder_popup_menu =
             gtk::Builder::new_from_string(include_str!(concat!(env!("CARGO_MANIFEST_DIR"),
                                                                "/data/ui/popup-menu.glade")));
-        let prefs = RefCell::new(unwrap_error!(Prefs::new(), None));
 
 
-        let card_name = prefs.borrow()
-            .device_prefs
-            .card
-            .clone();
-        let chan_name = prefs.borrow()
-            .device_prefs
-            .channel
-            .clone();
         // TODO: better error handling
         #[cfg(feature = "notify")]
         let notif = result_warn!(Notif::new(&prefs.borrow()), None).ok();
 
-        let audio = Rc::new(unwrap_error!(Audio::new(Some(card_name),
-                                                     Some(chan_name)),
-                                          None));
-        let hotkeys = unwrap_error!(wresult_warn!(Hotkeys::new(&prefs.borrow(),
-            audio.clone()), None),
+
+        let hotkeys = unwrap_error!(wresult_warn!(
+                    Hotkeys::new(&prefs.borrow(),
+                                 audio.clone()), None),
                                     None);
 
         let gui =
@@ -72,7 +86,7 @@ impl AppS {
         return AppS {
                    _cant_construct: (),
                    gui,
-                   audio: audio,
+                   audio,
                    prefs,
                    #[cfg(feature = "notify")]
                    notif,
@@ -87,14 +101,14 @@ impl AppS {
     pub fn update_tray_icon(&self) -> Result<()> {
         debug!("Update tray icon!");
         return self.gui.tray_icon.update_all(&self.prefs.borrow(),
-                                             &self.audio,
+                                             self.audio.as_ref(),
                                              None);
     }
 
     /// Update the Popup Window state.
     pub fn update_popup_window(&self) -> Result<()> {
         debug!("Update PopupWindow!");
-        return self.gui.popup_window.update(&self.audio);
+        return self.gui.popup_window.update(self.audio.as_ref());
     }
 
     #[cfg(feature = "notify")]
@@ -112,7 +126,7 @@ impl AppS {
 
     /// Update the audio state.
     pub fn update_audio(&self, user: AudioUser) -> Result<()> {
-        return audio_reload(&self.audio, &self.prefs.borrow(), user);
+        return audio_reload(self.audio.as_ref(), &self.prefs.borrow(), user);
     }
 
     /// Update the config file.
diff --git a/src/audio.rs b/src/audio.rs
index ead5e92c3..8d284fb5f 100644
--- a/src/audio.rs
+++ b/src/audio.rs
@@ -1,5 +1,4 @@
 #![allow(missing_docs)] // enums
-#![allow(illegal_floating_point_literal_pattern)]
 
 //! High-level audio subsystem.
 //!
@@ -9,15 +8,11 @@
 //! of the underlying audio implementation, may it be alsa or whatever.
 
 
-use alsa_card::*;
 use errors::*;
-use glib;
-use std::cell::Cell;
 use std::cell::Ref;
 use std::cell::RefCell;
 use std::f64;
 use std::rc::Rc;
-use support_alsa::*;
 use support_audio::*;
 
 
@@ -65,162 +60,39 @@ pub struct Handlers {
 
 
 impl Handlers {
-    fn new() -> Handlers {
+    pub fn new() -> Handlers {
         return Handlers { inner: Rc::new(RefCell::new(vec![])) };
     }
 
 
-    fn borrow(&self) -> Ref<Vec<Box<Fn(AudioSignal, AudioUser)>>> {
+    pub fn borrow(&self) -> Ref<Vec<Box<Fn(AudioSignal, AudioUser)>>> {
         return self.inner.borrow();
     }
 
 
-    fn add_handler(&self, cb: Box<Fn(AudioSignal, AudioUser)>) {
+    pub fn add_handler(&self, cb: Box<Fn(AudioSignal, AudioUser)>) {
         self.inner.borrow_mut().push(cb);
     }
 }
 
 
-/// High-level Audio struct, which could theoretically be backend
-/// agnostic.
-pub struct Audio {
-    _cannot_construct: (),
-    /// The alsa card.
-    pub acard: RefCell<Box<AlsaCard>>,
-    /// Last timestamp of an internal action we triggered, e.g.
-    /// by setting the volume or the mute state.
-    pub last_action_timestamp: Rc<RefCell<i64>>,
-    /// A set of handlers that react to audio signals. We can
-    /// connect to these.
-    pub handlers: Handlers,
-    /// The step at which to increase/decrease the volume.
-    /// This value is basically from the preferences.
-    pub scroll_step: Cell<u32>,
-}
-
-
-impl Audio {
-    /// Create a new Audio instance. This tries very hard to get
-    /// a working configuration from the backend.
-    /// ## `card_name`
-    /// If a card name is provided, it will be tried. If `None` is provided
-    /// or the given card name does not exist or is not playable, any other
-    /// playable card is tried.
-    /// ## `elem_name`
-    /// If an elem name is provided, it will be tried. If `None` is provided
-    /// or the given elem name does not exist or is not playable, any other
-    /// playable elem is tried.
-    ///
-    /// # Returns
-    ///
-    /// `Ok(Audio)` on success, `Err(error)` otherwise.
-    pub fn new(card_name: Option<String>,
-               elem_name: Option<String>)
-               -> Result<Audio> {
-
-        let handlers = Handlers::new();
-        let last_action_timestamp = Rc::new(RefCell::new(0));
-
-        let cb = {
-            let myhandler = handlers.clone();
-            let ts = last_action_timestamp.clone();
-            Rc::new(move |event| {
-                        on_alsa_event(&mut *ts.borrow_mut(),
-                                      &myhandler.borrow(),
-                                      event)
-                    })
-        };
-
-        let acard = AlsaCard::new(card_name, elem_name, cb);
-
-        /* additionally dispatch signals */
-        if acard.is_err() {
-            invoke_handlers(&handlers.borrow(),
-                            AudioSignal::NoCard,
-                            AudioUser::Unknown);
-        } else {
-            invoke_handlers(&handlers.borrow(),
-                            AudioSignal::CardInitialized,
-                            AudioUser::Unknown);
-        }
-
-        let audio = Audio {
-            _cannot_construct: (),
-            acard: RefCell::new(acard?),
-            last_action_timestamp: last_action_timestamp.clone(),
-            handlers: handlers.clone(),
-            scroll_step: Cell::new(5),
-        };
-
-        return Ok(audio);
-    }
-
-
-    /// Switches the current alsa card. Behaves the same way in regards to
-    /// `card_name` and `elem_name` as the `Audio::new()` method.
+// TODO: explain more, specify details that need to be implemented
+pub trait AudioFrontend {
+    /// Switches the current card. Must invoke handlers.
     /// ## `user`
     /// Where the card switch originates from.
-    pub fn switch_acard(&self,
-                        card_name: Option<String>,
-                        elem_name: Option<String>,
-                        user: AudioUser)
-                        -> Result<()> {
-        debug!("Switching cards");
-        debug!("Old card name: {}",
-               self.acard
-                   .borrow()
-                   .card_name()
-                   .unwrap());
-        debug!("Old chan name: {}",
-               self.acard
-                   .borrow()
-                   .chan_name()
-                   .unwrap());
-        let cb = self.acard
-            .borrow()
-            .cb
-            .clone();
-        {
-            let mut ac = self.acard.borrow_mut();
-            *ac = AlsaCard::new(card_name, elem_name, cb)?;
-        }
+    fn switch_card(&self,
+                   card_name: Option<String>,
+                   elem_name: Option<String>,
+                   user: AudioUser)
+                   -> Result<()>;
 
-        invoke_handlers(&self.handlers.borrow(),
-                        AudioSignal::CardInitialized,
-                        user);
+    /// Current volume. Between 0 and 100.
+    /// This always gets the volume of the `FrontRight` channel, because the
+    /// seems to be the safest bet.
+    fn get_vol(&self) -> Result<f64>;
 
-        return Ok(());
-    }
-
-
-    /// Current volume.
-    pub fn vol(&self) -> Result<f64> {
-        let alsa_vol = self.acard
-            .borrow()
-            .get_vol()?;
-        return vol_to_percent(alsa_vol, self.acard.borrow().get_volume_range());
-    }
-
-
-    /// Current volume level, nicely usable for e.g. selecting from a set
-    /// of images.
-    pub fn vol_level(&self) -> VolLevel {
-        let muted = self.get_mute().unwrap_or(false);
-        if muted {
-            return VolLevel::Muted;
-        }
-        let cur_vol = try_r!(self.vol(), VolLevel::Muted);
-        match cur_vol {
-            0. => return VolLevel::Off,
-            0.0...33.0 => return VolLevel::Low,
-            0.0...66.0 => return VolLevel::Medium,
-            0.0...100.0 => return VolLevel::High,
-            _ => return VolLevel::Off,
-        }
-    }
-
-
-    /// Set the current volume.
+    /// Set the current volume. Must invoke handlers.
     /// ## `new_vol`
     /// Set the volume to this value.
     /// ## `user`
@@ -230,219 +102,60 @@ impl Audio {
     /// or increase. This helps with rounding problems.
     /// ## `auto_unmute`
     /// Whether to automatically unmute if the volume changes.
-    pub fn set_vol(&self,
-                   new_vol: f64,
-                   user: AudioUser,
-                   dir: VolDir,
-                   auto_unmute: bool)
-                   -> Result<()> {
-        {
-            let mut rc = self.last_action_timestamp.borrow_mut();
-            *rc = glib::get_monotonic_time();
-        }
-
-        let alsa_vol = percent_to_vol(new_vol,
-                                      self.acard.borrow().get_volume_range(),
-                                      dir)?;
-
-        /* only invoke handlers etc. if volume did actually change */
-        {
-            let old_alsa_vol =
-                percent_to_vol(self.vol()?,
-                               self.acard.borrow().get_volume_range(),
-                               dir)?;
-
-            if old_alsa_vol == alsa_vol {
-                return Ok(());
-            }
-        }
-
-        /* auto-unmute */
-        if auto_unmute && self.has_mute() && self.get_mute()? {
-            self.set_mute(false, user)?;
-        }
-
-        debug!("Setting vol on card {:?} and chan {:?} to {:?} by user {:?}",
-               self.acard
-                   .borrow()
-                   .card_name()
-                   .unwrap(),
-               self.acard
-                   .borrow()
-                   .chan_name()
-                   .unwrap(),
-               new_vol,
-               user);
-
-        self.acard
-            .borrow()
-            .set_vol(alsa_vol)?;
-
-        invoke_handlers(&self.handlers.borrow(),
-                        AudioSignal::ValuesChanged,
-                        user);
-        return Ok(());
-    }
+    fn set_vol(&self,
+               new_vol: f64,
+               user: AudioUser,
+               dir: VolDir,
+               auto_unmute: bool)
+               -> Result<()>;
 
+    /// Current volume level, nicely usable for e.g. selecting from a set
+    /// of images.
+    fn vol_level(&self) -> VolLevel;
 
     /// Increase the volume. The step to increasy by is taken from
     /// `self.scroll_step`.
     /// ## `user`
     /// Where the card switch originates from.
-    pub fn increase_vol(&self,
-                        user: AudioUser,
-                        auto_unmute: bool)
-                        -> Result<()> {
-        let old_vol = self.vol()?;
-        let new_vol = old_vol + (self.scroll_step.get() as f64);
-
-        return self.set_vol(new_vol, user, VolDir::Up, auto_unmute);
-    }
-
+    fn increase_vol(&self, user: AudioUser, auto_unmute: bool) -> Result<()>;
 
     /// Decrease the volume. The step to decrease by is taken from
     /// `self.scroll_step`.
     /// ## `user`
     /// Where the card switch originates from.
-    pub fn decrease_vol(&self,
-                        user: AudioUser,
-                        auto_unmute: bool)
-                        -> Result<()> {
-        let old_vol = self.vol()?;
-        let new_vol = old_vol - (self.scroll_step.get() as f64);
-
-        return self.set_vol(new_vol, user, VolDir::Down, auto_unmute);
-    }
-
+    fn decrease_vol(&self, user: AudioUser, auto_unmute: bool) -> Result<()>;
 
     /// Whether the current audio configuration can be muted.
-    pub fn has_mute(&self) -> bool {
-        return self.acard.borrow().has_mute();
-    }
-
+    fn has_mute(&self) -> bool;
 
     /// Get the mute state of the current audio configuration.
-    pub fn get_mute(&self) -> Result<bool> {
-        return self.acard.borrow().get_mute();
-    }
-
+    fn get_mute(&self) -> Result<bool>;
 
     /// Set the mute state of the current audio configuration.
-    pub fn set_mute(&self, mute: bool, user: AudioUser) -> Result<()> {
-        let mut rc = self.last_action_timestamp.borrow_mut();
-        *rc = glib::get_monotonic_time();
-
-        debug!("Setting mute to {} on card {:?} and chan {:?} by user {:?}",
-               mute,
-               self.acard
-                   .borrow()
-                   .card_name()
-                   .unwrap(),
-               self.acard
-                   .borrow()
-                   .chan_name()
-                   .unwrap(),
-               user);
-
-        self.acard
-            .borrow()
-            .set_mute(mute)?;
-
-        invoke_handlers(&self.handlers.borrow(),
-                        AudioSignal::ValuesChanged,
-                        user);
-        return Ok(());
-    }
-
+    /// Must invoke handlers.
+    fn set_mute(&self, mute: bool, user: AudioUser) -> Result<()>;
 
     /// Toggle the mute state of the current audio configuration.
-    pub fn toggle_mute(&self, user: AudioUser) -> Result<()> {
-        let muted = self.get_mute()?;
-        return self.set_mute(!muted, user);
-    }
-
+    fn toggle_mute(&self, user: AudioUser) -> Result<()>;
 
     /// Connect a signal handler to the audio subsystem. This can
     /// be done from anywhere, e.g. in the UI code to react to
     /// certain signals. Multiple handlers for the same signals are fine,
     /// they will be executed in order.
-    pub fn connect_handler(&self, cb: Box<Fn(AudioSignal, AudioUser)>) {
-        self.handlers.add_handler(cb);
-    }
-
+    fn connect_handler(&self, cb: Box<Fn(AudioSignal, AudioUser)>);
 
     /// Get the current card name.
-    pub fn card_name(&self) -> Result<String> {
-        return self.acard.borrow().card_name();
-    }
-
+    fn card_name(&self) -> Result<String>;
 
     /// Get the currently playable channel names.
-    pub fn playable_chan_names(&self) -> Vec<String> {
-        return get_playable_selem_names(&self.acard.borrow().mixer);
-    }
-
+    fn playable_chan_names(&self) -> Vec<String>;
 
     /// Get the current active channel name.
-    pub fn chan_name(&self) -> Result<String> {
-        return self.acard.borrow().chan_name();
-    }
-}
-
-
-/// Invokes the registered handlers.
-fn invoke_handlers(handlers: &Vec<Box<Fn(AudioSignal, AudioUser)>>,
-                   signal: AudioSignal,
-                   user: AudioUser) {
-    debug!("Invoking handlers for signal {:?} by user {:?}",
-           signal,
-           user);
-    if handlers.is_empty() {
-        debug!("No handler found");
-    } else {
-        debug!("Executing handlers")
-    }
-    for handler in handlers {
-        let unboxed = handler.as_ref();
-        unboxed(signal, user);
-    }
-}
-
-
-/// The callback for alsa events that is passed to the alsa subsystem.
-/// This is the bridge between low-level alsa events and "high-level"
-/// audio system signals.
-fn on_alsa_event(last_action_timestamp: &mut i64,
-                 handlers: &Vec<Box<Fn(AudioSignal, AudioUser)>>,
-                 alsa_event: AlsaEvent) {
-    let last: i64 = *last_action_timestamp;
-
-    if last != 0 {
-        let now: i64 = glib::get_monotonic_time();
-        let delay: i64 = now - last;
-        if delay < 1000000 {
-            return;
-        }
-        debug!("Discarding last time stamp, too old");
-        *last_action_timestamp = 0;
-    }
-
-    /* external change */
-    match alsa_event {
-        AlsaEvent::AlsaCardError => {
-            invoke_handlers(handlers,
-                            self::AudioSignal::CardError,
-                            self::AudioUser::Unknown);
-        }
-        AlsaEvent::AlsaCardDiconnected => {
-            invoke_handlers(handlers,
-                            self::AudioSignal::CardDisconnected,
-                            self::AudioUser::Unknown);
-        }
-        AlsaEvent::AlsaCardValuesChanged => {
-            invoke_handlers(handlers,
-                            self::AudioSignal::ValuesChanged,
-                            self::AudioUser::Unknown);
-        }
-    }
+    fn chan_name(&self) -> Result<String>;
+
+    /// Set the scroll step.
+    fn set_scroll_step(&self, scroll_step: u32);
+
+    /// Get the scroll step.
+    fn get_scroll_step(&self) -> u32;
 }
diff --git a/src/bin.rs b/src/bin.rs
index c9e3ad975..2022c37cd 100644
--- a/src/bin.rs
+++ b/src/bin.rs
@@ -18,7 +18,7 @@ fn main() {
        .init(Some("pnmixer=debug".to_string()))
        .unwrap_or_else(|e| panic!("Logger initialization failed with {}", e));
 
-    let apps = Rc::new(AppS::new());
+    let apps = Rc::new(new_alsa_appstate());
 
     ui_entry::init(apps);
 
diff --git a/src/hotkeys.rs b/src/hotkeys.rs
index edb5a0726..d4cc4c610 100644
--- a/src/hotkeys.rs
+++ b/src/hotkeys.rs
@@ -5,7 +5,7 @@
 //! before they can be interpreted by Gtk/Gdk.
 
 
-use audio::{Audio, AudioUser};
+use audio::*;
 use errors::*;
 use errors;
 use gdk;
@@ -23,22 +23,26 @@ use x11;
 
 
 /// The possible Hotkeys for manipulating the volume.
-pub struct Hotkeys {
+pub struct Hotkeys<T>
+    where T: AudioFrontend
+{
     enabled: bool,
     mute_key: Option<Hotkey>,
     up_key: Option<Hotkey>,
     down_key: Option<Hotkey>,
 
     // need this to access audio in 'key_filter'
-    audio: Rc<Audio>,
+    audio: Rc<T>,
     auto_unmute: bool,
 }
 
-impl Hotkeys {
+impl<T> Hotkeys<T>
+    where T: AudioFrontend
+{
     /// Creates the hotkeys subsystem and binds the hotkeys.
     pub fn new(prefs: &Prefs,
-               audio: Rc<Audio>)
-               -> WResult<Box<Hotkeys>, errors::Error, errors::Error> {
+               audio: Rc<T>)
+               -> WResult<Box<Hotkeys<T>>, errors::Error, errors::Error> {
         debug!("Creating hotkeys control");
         let mut hotkeys =
             Box::new(Hotkeys {
@@ -55,10 +59,10 @@ impl Hotkeys {
         /* bind hotkeys */
         let data_ptr =
             unsafe {
-                mem::transmute::<&Hotkeys,
+                mem::transmute::<&Hotkeys<T>,
                                  glib_sys::gpointer>(hotkeys.as_ref())
             };
-        hotkeys_add_filter(Some(key_filter), data_ptr);
+        hotkeys_add_filter(Some(key_filter::<T>), data_ptr);
         return WOk(hotkeys, warn);
     }
 
@@ -159,8 +163,8 @@ impl Hotkeys {
         }
 
         let data_ptr =
-            unsafe { mem::transmute::<&Hotkeys, glib_sys::gpointer>(self) };
-        hotkeys_add_filter(Some(key_filter), data_ptr);
+            unsafe { mem::transmute::<&Hotkeys<T>, glib_sys::gpointer>(self) };
+        hotkeys_add_filter(Some(key_filter::<T>), data_ptr);
     }
 
     /// Unbind hotkeys manually. Should be paired with a `bind()` call.
@@ -186,22 +190,25 @@ impl Hotkeys {
         }
 
         let data_ptr =
-            unsafe { mem::transmute::<&Hotkeys, glib_sys::gpointer>(self) };
-        hotkeys_remove_filter(Some(key_filter), data_ptr);
+            unsafe { mem::transmute::<&Hotkeys<T>, glib_sys::gpointer>(self) };
+        hotkeys_remove_filter(Some(key_filter::<T>), data_ptr);
     }
 }
 
-impl Drop for Hotkeys {
+impl<T> Drop for Hotkeys<T>
+    where T: AudioFrontend
+{
     fn drop(&mut self) {
         debug!("Freeing hotkeys");
         self.mute_key = None;
         self.up_key = None;
         self.down_key = None;
 
-        let data_ptr =
-            unsafe { mem::transmute::<&mut Hotkeys, glib_sys::gpointer>(self) };
+        let data_ptr = unsafe {
+            mem::transmute::<&mut Hotkeys<T>, glib_sys::gpointer>(self)
+        };
 
-        hotkeys_remove_filter(Some(key_filter), data_ptr)
+        hotkeys_remove_filter(Some(key_filter::<T>), data_ptr)
     }
 }
 
@@ -243,14 +250,16 @@ fn hotkeys_remove_filter(function: gdk_sys::GdkFilterFunc,
 
 /// This function is called before Gtk/Gdk can respond
 /// to any(!) window event and handles pressed hotkeys.
-extern "C" fn key_filter(gdk_xevent: *mut gdk_sys::GdkXEvent,
-                         _: *mut gdk_sys::GdkEvent,
-                         data: glib_sys::gpointer)
-                         -> gdk_sys::GdkFilterReturn {
+extern "C" fn key_filter<T>(gdk_xevent: *mut gdk_sys::GdkXEvent,
+                            _: *mut gdk_sys::GdkEvent,
+                            data: glib_sys::gpointer)
+                            -> gdk_sys::GdkFilterReturn
+    where T: AudioFrontend
+{
     let xevent = gdk_xevent as *mut x11::xlib::XKeyEvent;
 
-    let hotkeys: &Hotkeys =
-        unsafe { mem::transmute::<glib_sys::gpointer, &Hotkeys>(data) };
+    let hotkeys: &Hotkeys<T> =
+        unsafe { mem::transmute::<glib_sys::gpointer, &Hotkeys<T>>(data) };
     let mute_key = &hotkeys.mute_key;
     let up_key = &hotkeys.up_key;
     let down_key = &hotkeys.down_key;
diff --git a/src/lib.rs b/src/lib.rs
index fd41ab17c..f60dd4b42 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -97,4 +97,3 @@ pub mod ui_tray_icon;
 
 #[cfg(feature = "notify")]
 pub mod notif;
-
diff --git a/src/notif.rs b/src/notif.rs
index e12cbcdd9..a7e40fc20 100644
--- a/src/notif.rs
+++ b/src/notif.rs
@@ -73,8 +73,10 @@ impl Notif {
     }
 
     /// Shows a volume notification, e.g. for volume or mute state change.
-    pub fn show_volume_notif(&self, audio: &Audio) -> Result<()> {
-        let vol = audio.vol()?;
+    pub fn show_volume_notif<T>(&self, audio: &T) -> Result<()>
+        where T: AudioFrontend
+    {
+        let vol = audio.get_vol()?;
         let vol_level = audio.vol_level();
 
         let icon = {
@@ -92,12 +94,8 @@ impl Notif {
                 VolLevel::Muted => String::from("Volume muted"),
                 _ => {
                     format!("{} ({})\nVolume: {}",
-                            audio.acard
-                                .borrow()
-                                .card_name()?,
-                            audio.acard
-                                .borrow()
-                                .chan_name()?,
+                            audio.card_name()?,
+                            audio.chan_name()?,
                             vol as i32)
                 }
             }
@@ -133,7 +131,9 @@ impl Drop for Notif {
 
 
 /// Initialize the notification subsystem.
-pub fn init_notify(appstate: Rc<AppS>) {
+pub fn init_notify<T>(appstate: Rc<AppS<T>>)
+    where T: AudioFrontend + 'static
+{
     {
         /* connect handler */
         let apps = appstate.clone();
@@ -154,16 +154,16 @@ pub fn init_notify(appstate: Rc<AppS>) {
                 (AudioSignal::CardError, _, _) => (),
                 (AudioSignal::ValuesChanged,
                  AudioUser::TrayIcon,
-                 (_, true, _, _)) => try_w!(notif.show_volume_notif(&apps.audio)),
+                 (_, true, _, _)) => try_w!(notif.show_volume_notif(apps.audio.as_ref())),
                 (AudioSignal::ValuesChanged,
                  AudioUser::Popup,
-                 (true, _, _, _)) => try_w!(notif.show_volume_notif(&apps.audio)),
+                 (true, _, _, _)) => try_w!(notif.show_volume_notif(apps.audio.as_ref())),
                 (AudioSignal::ValuesChanged,
                  AudioUser::Unknown,
-                 (_, _, true, _)) => try_w!(notif.show_volume_notif(&apps.audio)),
+                 (_, _, true, _)) => try_w!(notif.show_volume_notif(apps.audio.as_ref())),
                 (AudioSignal::ValuesChanged,
                  AudioUser::Hotkeys,
-                 (_, _, _, true)) => try_w!(notif.show_volume_notif(&apps.audio)),
+                 (_, _, _, true)) => try_w!(notif.show_volume_notif(apps.audio.as_ref())),
                 _ => (),
             }
         }));
diff --git a/src/support_audio.rs b/src/support_audio.rs
index 9a9b9d87c..7082a3e1e 100644
--- a/src/support_audio.rs
+++ b/src/support_audio.rs
@@ -6,7 +6,7 @@
 //! but are important helpers.
 
 
-use audio::{Audio, AudioUser};
+use audio::*;
 use errors::*;
 use prefs::*;
 use support_alsa::*;
@@ -54,14 +54,13 @@ pub fn lrint(v: f64, dir: VolDir) -> f64 {
 
 
 /// Reload the audio system.
-pub fn audio_reload(audio: &Audio,
-                    prefs: &Prefs,
-                    user: AudioUser)
-                    -> Result<()> {
+pub fn audio_reload<T>(audio: &T, prefs: &Prefs, user: AudioUser) -> Result<()>
+    where T: AudioFrontend
+{
     let card = &prefs.device_prefs.card;
     let channel = &prefs.device_prefs.channel;
     // TODO: is this clone safe?
-    return audio.switch_acard(Some(card.clone()), Some(channel.clone()), user);
+    return audio.switch_card(Some(card.clone()), Some(channel.clone()), user);
 }
 
 
diff --git a/src/ui_entry.rs b/src/ui_entry.rs
index d5b4b93f5..972b089ab 100644
--- a/src/ui_entry.rs
+++ b/src/ui_entry.rs
@@ -2,7 +2,7 @@
 
 
 use app_state::*;
-use audio::{AudioUser, AudioSignal};
+use audio::*;
 use gtk::DialogExt;
 use gtk::MessageDialogExt;
 use gtk::WidgetExt;
@@ -56,20 +56,22 @@ impl Gui {
 
 
 /// Initialize the GUI system.
-pub fn init(appstate: Rc<AppS>) {
+pub fn init<T>(appstate: Rc<AppS<T>>)
+    where T: AudioFrontend + 'static
+{
     {
         /* "global" audio signal handler */
         let apps = appstate.clone();
         appstate.audio.connect_handler(
         Box::new(move |s, u| match (s, u) {
             (AudioSignal::CardDisconnected, _) => {
-                 try_w!(audio_reload(&apps.audio,
+                 try_w!(audio_reload(apps.audio.as_ref(),
                          &apps.prefs.borrow(),
                          AudioUser::Unknown));
             },
             (AudioSignal::CardError, _) => {
                 if run_audio_error_dialog(&apps.gui.popup_menu.menu_window) == (GTK_RESPONSE_YES as i32) {
-                     try_w!(audio_reload(&apps.audio,
+                     try_w!(audio_reload(apps.audio.as_ref(),
                              &apps.prefs.borrow(),
                              AudioUser::Unknown));
                 }
diff --git a/src/ui_popup_menu.rs b/src/ui_popup_menu.rs
index dc25cc69a..0e7a7f281 100644
--- a/src/ui_popup_menu.rs
+++ b/src/ui_popup_menu.rs
@@ -12,7 +12,7 @@
 //! * Quit
 
 use app_state::*;
-use audio::AudioUser;
+use audio::*;
 use gtk::prelude::*;
 use gtk;
 use std::rc::Rc;
@@ -40,7 +40,9 @@ create_builder_item!(PopupMenu,
 
 
 /// Initialize the popup menu subsystem, registering all callbacks.
-pub fn init_popup_menu(appstate: Rc<AppS>) {
+pub fn init_popup_menu<T>(appstate: Rc<AppS<T>>)
+    where T: AudioFrontend + 'static
+{
     /* audio.connect_handler */
     {
         let apps = appstate.clone();
@@ -113,7 +115,7 @@ pub fn init_popup_menu(appstate: Rc<AppS>) {
         let apps = appstate.clone();
         let reload_item = &appstate.gui.popup_menu.reload_item;
         reload_item.connect_activate(move |_| {
-                                         try_w!(audio_reload(&apps.audio,
+                                         try_w!(audio_reload(apps.audio.as_ref(),
                                                  &apps.prefs.borrow(),
                                                  AudioUser::Popup))
                                      });
@@ -129,7 +131,9 @@ pub fn init_popup_menu(appstate: Rc<AppS>) {
 
 
 /// When the about menu item is activated.
-fn on_about_item_activate(appstate: &AppS) {
+fn on_about_item_activate<T>(appstate: &AppS<T>)
+    where T: AudioFrontend
+{
     let popup_menu = &appstate.gui.popup_menu.menu_window;
     let about_dialog = create_about_dialog();
     about_dialog.set_skip_taskbar_hint(true);
@@ -171,14 +175,18 @@ Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.",
 
 
 /// When the Preferences item is activated.
-fn on_prefs_item_activate(appstate: &Rc<AppS>) {
+fn on_prefs_item_activate<T>(appstate: &Rc<AppS<T>>)
+    where T: AudioFrontend + 'static
+{
     /* TODO: only create if needed */
     show_prefs_dialog(appstate);
 }
 
 
 /// When the Mute item is checked.
-fn set_mute_check(apps: &Rc<AppS>) {
+fn set_mute_check<T>(apps: &Rc<AppS<T>>)
+    where T: AudioFrontend
+{
     let mute_check = &apps.gui.popup_menu.mute_check;
     let m_muted = apps.audio.get_mute();
     match m_muted {
diff --git a/src/ui_popup_window.rs b/src/ui_popup_window.rs
index 1fc0af032..1efe4609f 100644
--- a/src/ui_popup_window.rs
+++ b/src/ui_popup_window.rs
@@ -62,17 +62,21 @@ impl PopupWindow {
 
     /// Update the popup window state, including the slider
     /// and the mute checkbutton.
-    pub fn update(&self, audio: &Audio) -> Result<()> {
-        let cur_vol = audio.vol()?;
+    pub fn update<T>(&self, audio: &T) -> Result<()>
+        where T: AudioFrontend
+    {
+        let cur_vol = audio.get_vol()?;
         set_slider(&self.vol_scale_adj, cur_vol);
 
-        self.update_mute_check(&audio);
+        self.update_mute_check(audio);
 
         return Ok(());
     }
 
     /// Update the mute checkbutton.
-    pub fn update_mute_check(&self, audio: &Audio) {
+    pub fn update_mute_check<T>(&self, audio: &T)
+        where T: AudioFrontend
+    {
         let m_muted = audio.get_mute();
 
         glib::signal_handler_block(&self.mute_check, self.toggle_signal.get());
@@ -109,7 +113,9 @@ impl PopupWindow {
 
 
 /// Initialize the popup window subsystem.
-pub fn init_popup_window(appstate: Rc<AppS>) {
+pub fn init_popup_window<T>(appstate: Rc<AppS<T>>)
+    where T: AudioFrontend + 'static
+{
     /* audio.connect_handler */
     {
         let apps = appstate.clone();
@@ -130,11 +136,12 @@ pub fn init_popup_window(appstate: Rc<AppS>) {
                  * and not the real value reported by the audio system.
                  */
                 (_, AudioUser::Popup) => {
-                    apps.gui.popup_window.update_mute_check(&apps.audio);
+                    apps.gui.popup_window.update_mute_check(apps.audio
+                                                                .as_ref());
                 }
                 /* external change, safe to update slider too */
                 (_, _) => {
-                    try_w!(apps.gui.popup_window.update(&apps.audio));
+                    try_w!(apps.gui.popup_window.update(apps.audio.as_ref()));
                 }
             }
         }));
@@ -213,12 +220,14 @@ pub fn init_popup_window(appstate: Rc<AppS>) {
 
 
 /// When the popup window is shown.
-fn on_popup_window_show(appstate: &AppS) {
+fn on_popup_window_show<T>(appstate: &AppS<T>)
+    where T: AudioFrontend
+{
     let popup_window = &appstate.gui.popup_window;
     appstate.gui.popup_window.set_vol_increment(&appstate.prefs.borrow());
     glib::signal_handler_block(&popup_window.vol_scale_adj,
                                popup_window.changed_signal.get());
-    try_w!(appstate.gui.popup_window.update(&appstate.audio));
+    try_w!(appstate.gui.popup_window.update(appstate.audio.as_ref()));
     glib::signal_handler_unblock(&popup_window.vol_scale_adj,
                                  popup_window.changed_signal.get());
     popup_window.vol_scale.grab_focus();
@@ -257,9 +266,11 @@ fn on_popup_window_event(w: &gtk::Window, e: &gdk::Event) -> gtk::Inhibit {
 
 
 /// When the volume scale slider is moved.
-fn on_vol_scale_value_changed(appstate: &AppS) {
+fn on_vol_scale_value_changed<T>(appstate: &AppS<T>)
+    where T: AudioFrontend
+{
     let audio = &appstate.audio;
-    let old_vol = try_w!(audio.vol());
+    let old_vol = try_w!(audio.get_vol());
 
     let val = appstate.gui
         .popup_window
@@ -279,7 +290,9 @@ fn on_vol_scale_value_changed(appstate: &AppS) {
 
 
 /// When the mute checkbutton is toggled.
-fn on_mute_check_toggled(appstate: &AppS) {
+fn on_mute_check_toggled<T>(appstate: &AppS<T>)
+    where T: AudioFrontend
+{
     let audio = &appstate.audio;
     try_w!(audio.toggle_mute(AudioUser::Popup))
 }
diff --git a/src/ui_prefs_dialog.rs b/src/ui_prefs_dialog.rs
index 88eb15e72..736e3ceed 100644
--- a/src/ui_prefs_dialog.rs
+++ b/src/ui_prefs_dialog.rs
@@ -3,7 +3,7 @@
 
 
 use app_state::*;
-use audio::{AudioUser, AudioSignal};
+use audio::*;
 use errors::*;
 use gdk;
 use gtk::ResponseType;
@@ -334,7 +334,9 @@ impl PrefsDialog {
 
 /// Show the preferences dialog. This is created and destroyed dynamically
 /// and not persistent across the application lifetime.
-pub fn show_prefs_dialog(appstate: &Rc<AppS>) {
+pub fn show_prefs_dialog<T>(appstate: &Rc<AppS<T>>)
+    where T: AudioFrontend + 'static
+{
     if appstate.gui
            .prefs_dialog
            .borrow()
@@ -359,7 +361,9 @@ pub fn show_prefs_dialog(appstate: &Rc<AppS>) {
 
 /// Initialize the internal prefs dialog handler that connects to the audio
 /// system.
-pub fn init_prefs_callback(appstate: Rc<AppS>) {
+pub fn init_prefs_callback<T>(appstate: Rc<AppS<T>>)
+    where T: AudioFrontend + 'static
+{
     let apps = appstate.clone();
     appstate.audio.connect_handler(Box::new(move |s, u| {
         /* skip if prefs window is not present */
@@ -383,7 +387,9 @@ pub fn init_prefs_callback(appstate: Rc<AppS>) {
 
 
 /// Initialize the preferences dialog gtk callbacks.
-fn init_prefs_dialog(appstate: &Rc<AppS>) {
+fn init_prefs_dialog<T>(appstate: &Rc<AppS<T>>)
+    where T: AudioFrontend + 'static
+{
 
     /* prefs_dialog.connect_show */
     {
@@ -486,7 +492,9 @@ fn init_prefs_dialog(appstate: &Rc<AppS>) {
 
 
 /// Fill the card combo box in the Devices tab.
-fn fill_card_combo(appstate: &AppS) {
+fn fill_card_combo<T>(appstate: &AppS<T>)
+    where T: AudioFrontend
+{
     let m_cc = appstate.gui.prefs_dialog.borrow();
     let card_combo = &m_cc.as_ref().unwrap().card_combo;
     card_combo.remove_all();
@@ -513,7 +521,9 @@ fn fill_card_combo(appstate: &AppS) {
 
 
 /// Fill the channel combo box in the Devices tab.
-fn fill_chan_combo(appstate: &AppS, cardname: Option<String>) {
+fn fill_chan_combo<T>(appstate: &AppS<T>, cardname: Option<String>)
+    where T: AudioFrontend
+{
     let m_cc = appstate.gui.prefs_dialog.borrow();
     let chan_combo = &m_cc.as_ref().unwrap().chan_combo;
     chan_combo.remove_all();
@@ -543,10 +553,12 @@ fn fill_chan_combo(appstate: &AppS, cardname: Option<String>) {
 }
 
 
-fn on_hotkey_event_box_button_press_event(appstate: &AppS,
-                                          widget: &gtk::EventBox,
-                                          event: &gdk::EventButton)
-                                          -> bool {
+fn on_hotkey_event_box_button_press_event<T>(appstate: &AppS<T>,
+                                             widget: &gtk::EventBox,
+                                             event: &gdk::EventButton)
+                                             -> bool
+    where T: AudioFrontend
+{
     let borrow = appstate.gui.prefs_dialog.borrow();
     let prefs_dialog = &borrow.as_ref().unwrap();
     /* we want a left-click */
diff --git a/src/ui_tray_icon.rs b/src/ui_tray_icon.rs
index 4049b1b14..3ebd52ac4 100644
--- a/src/ui_tray_icon.rs
+++ b/src/ui_tray_icon.rs
@@ -96,16 +96,14 @@ impl TrayIcon {
 
 
     /// Update the tooltip of the tray icon.
-    fn update_tooltip(&self, audio: &Audio) {
-        let cardname = audio.acard
-            .borrow()
-            .card_name()
-            .unwrap_or(String::from("Unknown card"));
-        let channame = audio.acard
-            .borrow()
-            .chan_name()
-            .unwrap_or(String::from("unknown channel"));
-        let vol = audio.vol()
+    fn update_tooltip<T>(&self, audio: &T)
+        where T: AudioFrontend
+    {
+        let cardname =
+            audio.card_name().unwrap_or(String::from("Unknown card"));
+        let channame =
+            audio.chan_name().unwrap_or(String::from("unknown channel"));
+        let vol = audio.get_vol()
             .map(|s| format!("{}", s.round()))
             .unwrap_or(String::from("unknown volume"));
         let mute_info = {
@@ -127,11 +125,13 @@ impl TrayIcon {
 
 
     /// Update the whole tray icon state.
-    pub fn update_all(&self,
-                      prefs: &Prefs,
-                      audio: &Audio,
-                      m_size: Option<i32>)
-                      -> Result<()> {
+    pub fn update_all<T>(&self,
+                         prefs: &Prefs,
+                         audio: &T,
+                         m_size: Option<i32>)
+                         -> Result<()>
+        where T: AudioFrontend
+    {
         match m_size {
             Some(s) => {
                 if s < ICON_MIN_SIZE {
@@ -153,8 +153,8 @@ impl TrayIcon {
             *self.volmeter.borrow_mut() = Some(volmeter);
         }
 
-        self.update_tooltip(&audio);
-        return self.update_vol_meter(audio.vol()?, audio.vol_level());
+        self.update_tooltip(audio);
+        return self.update_vol_meter(audio.get_vol()?, audio.vol_level());
     }
 }
 
@@ -378,7 +378,9 @@ impl AudioPix {
 
 
 /// Initialize the tray icon subsystem.
-pub fn init_tray_icon(appstate: Rc<AppS>) {
+pub fn init_tray_icon<T>(appstate: Rc<AppS<T>>)
+    where T: AudioFrontend + 'static
+{
     let tray_icon = &appstate.gui.tray_icon;
 
     tray_icon.status_icon.set_visible(true);
@@ -388,9 +390,9 @@ pub fn init_tray_icon(appstate: Rc<AppS>) {
         let apps = appstate.clone();
         appstate.audio.connect_handler(Box::new(move |s, u| match (s, u) {
                                                     (_, _) => {
-            apps.gui.tray_icon.update_tooltip(&apps.audio);
+            apps.gui.tray_icon.update_tooltip(apps.audio.as_ref());
             try_w!(apps.gui.tray_icon.update_vol_meter(try_w!(apps.audio
-                                                                  .vol()),
+                                                                  .get_vol()),
                                                        apps.audio.vol_level()));
         }
                                                 }));
@@ -401,7 +403,7 @@ pub fn init_tray_icon(appstate: Rc<AppS>) {
         let apps = appstate.clone();
         tray_icon.status_icon.connect_size_changed(move |_, size| {
             try_wr!(apps.gui.tray_icon.update_all(&apps.prefs.borrow_mut(),
-                                                  &apps.audio,
+                                                  apps.audio.as_ref(),
                                                   Some(size)),
                     false);
             return false;
@@ -448,15 +450,17 @@ pub fn init_tray_icon(appstate: Rc<AppS>) {
                     ));
         default_theme.connect_changed(move |_| {
             let tray_icon = &apps.gui.tray_icon;
-            let audio = &apps.audio;
-            try_e!(tray_icon.update_all(&apps.prefs.borrow_mut(), &audio, None));
+            try_e!(tray_icon.update_all(&apps.prefs.borrow_mut(),
+                apps.audio.as_ref(), None));
         });
     }
 }
 
 
 /// When the tray icon is activated.
-fn on_tray_icon_activate(appstate: &AppS) {
+fn on_tray_icon_activate<T>(appstate: &AppS<T>)
+    where T: AudioFrontend
+{
     let popup_window = &appstate.gui.popup_window.popup_window;
 
     if popup_window.get_visible() {
@@ -468,7 +472,9 @@ fn on_tray_icon_activate(appstate: &AppS) {
 
 
 /// When the popup menu is shown, hide the popup window, if any.
-fn on_tray_icon_popup_menu(appstate: &AppS) {
+fn on_tray_icon_popup_menu<T>(appstate: &AppS<T>)
+    where T: AudioFrontend
+{
     let popup_window = &appstate.gui.popup_window.popup_window;
     let popup_menu = &appstate.gui.popup_menu.menu;
 
@@ -479,9 +485,11 @@ fn on_tray_icon_popup_menu(appstate: &AppS) {
 
 /// When the mouse scroll event happens while the mouse pointer is
 /// on the tray icon.
-fn on_tray_icon_scroll_event(appstate: &AppS,
-                             event: &gdk::EventScroll)
-                             -> bool {
+fn on_tray_icon_scroll_event<T>(appstate: &AppS<T>,
+                                event: &gdk::EventScroll)
+                                -> bool
+    where T: AudioFrontend
+{
 
     let scroll_dir: gdk::ScrollDirection = event.get_direction();
     match scroll_dir {
@@ -511,9 +519,11 @@ fn on_tray_icon_scroll_event(appstate: &AppS,
 /// Basically when the tray icon is clicked (although we connect to the `release`
 /// event). This decides whether it was a left, right or middle-click and
 /// takes appropriate actions.
-fn on_tray_button_release_event(appstate: &Rc<AppS>,
-                                event_button: &gdk::EventButton)
-                                -> bool {
+fn on_tray_button_release_event<T>(appstate: &Rc<AppS<T>>,
+                                   event_button: &gdk::EventButton)
+                                   -> bool
+    where T: AudioFrontend + 'static
+{
     let button = event_button.get_button();
 
     if button != 2 {