diff --git a/src/platform/windows/asio/asio_utils/mod.rs b/src/host/asio/asio_utils/mod.rs
similarity index 100%
rename from src/platform/windows/asio/asio_utils/mod.rs
rename to src/host/asio/asio_utils/mod.rs
diff --git a/src/platform/windows/asio/asio_utils/tests.rs b/src/host/asio/asio_utils/tests.rs
similarity index 100%
rename from src/platform/windows/asio/asio_utils/tests.rs
rename to src/host/asio/asio_utils/tests.rs
diff --git a/src/platform/windows/asio/device.rs b/src/host/asio/device.rs
similarity index 92%
rename from src/platform/windows/asio/device.rs
rename to src/host/asio/device.rs
index e31d9de..c6c085b 100644
--- a/src/platform/windows/asio/device.rs
+++ b/src/host/asio/device.rs
@@ -4,11 +4,12 @@ pub type SupportedOutputFormats = std::vec::IntoIter<SupportedFormat>;
 
 use std::hash::{Hash, Hasher};
 use DefaultFormatError;
+use DeviceNameError;
 use Format;
-use FormatsEnumerationError;
 use SampleFormat;
 use SampleRate;
 use SupportedFormat;
+use SupportedFormatsError;
 use super::sys;
 
 /// A ASIO Device
@@ -40,8 +41,8 @@ impl Hash for Device {
 }
 
 impl Device {
-    pub fn name(&self) -> String {
-        self.name.clone()
+    pub fn name(&self) -> Result<String, DeviceNameError> {
+        Ok(self.name.clone())
     }
 
     /// Gets the supported input formats.
@@ -49,11 +50,11 @@ impl Device {
     /// Need to find all possible formats.
     pub fn supported_input_formats(
         &self,
-    ) -> Result<SupportedInputFormats, FormatsEnumerationError> {
+    ) -> Result<SupportedInputFormats, SupportedFormatsError> {
         // Retrieve the default format for the total supported channels and supported sample
         // format.
         let mut f = match self.default_input_format() {
-            Err(_) => return Err(FormatsEnumerationError::DeviceNotAvailable),
+            Err(_) => return Err(SupportedFormatsError::DeviceNotAvailable),
             Ok(f) => f,
         };
 
@@ -77,11 +78,11 @@ impl Device {
     /// Need to find all possible formats.
     pub fn supported_output_formats(
         &self,
-    ) -> Result<SupportedOutputFormats, FormatsEnumerationError> {
+    ) -> Result<SupportedOutputFormats, SupportedFormatsError> {
         // Retrieve the default format for the total supported channels and supported sample
         // format.
         let mut f = match self.default_output_format() {
-            Err(_) => return Err(FormatsEnumerationError::DeviceNotAvailable),
+            Err(_) => return Err(SupportedFormatsError::DeviceNotAvailable),
             Ok(f) => f,
         };
 
@@ -140,12 +141,12 @@ impl Device {
     }
 }
 
-impl Default for Devices {
-    fn default() -> Devices {
+impl Devices {
+    pub fn new() -> Result<Self, DevicesError> {
         let driver_names = online_devices();
-        Devices {
+        Ok(Devices {
             drivers: driver_names.into_iter(),
-        }
+        })
     }
 }
 
diff --git a/src/host/asio/mod.rs b/src/host/asio/mod.rs
new file mode 100644
index 0000000..f1b22dc
--- /dev/null
+++ b/src/host/asio/mod.rs
@@ -0,0 +1,127 @@
+extern crate asio_sys as sys;
+
+use {
+    BuildStreamError,
+    DefaultFormatError,
+    Device as DeviceTrait,
+    DeviceNameError,
+    DevicesError,
+    EventLoop as EventLoopTrait,
+    Host as HostTrait,
+    PauseStreamError,
+    PlayStreamError,
+    StreamDataResult,
+    StreamId as StreamIdTrait,
+    SupportedFormatsError,
+}
+
+pub use self::device::{Device, Devices, SupportedInputFormats, SupportedOutputFormats, default_input_device, default_output_device};
+pub use self::stream::{EventLoop, StreamId};
+
+mod device;
+mod stream;
+mod asio_utils;
+
+/// The host for ASIO.
+#[derive(Debug)]
+pub struct Host;
+
+impl Host {
+    pub fn new() -> Result<Self, crate::HostUnavailable> {
+        unimplemented!("asio as an initialisation and termination process that needs to be impld");
+        //Ok(Host)
+    }
+}
+
+impl HostTrait for Host {
+    type Devices = Devices;
+    type Device = Device;
+    type EventLoop = EventLoop;
+
+    fn is_available() -> bool {
+        unimplemented!("check how to do this using asio-sys")
+    }
+
+    fn devices(&self) -> Result<Self::Devices, DevicesError> {
+        Devices::new()
+    }
+
+    fn default_input_device(&self) -> Option<Self::Device> {
+        default_input_device()
+    }
+
+    fn default_output_device(&self) -> Option<Self::Device> {
+        default_output_device()
+    }
+
+    fn event_loop(&self) -> Self::EventLoop {
+        EventLoop::new()
+    }
+}
+
+impl DeviceTrait for Device {
+    type SupportedInputFormats = SupportedInputFormats;
+    type SupportedOutputFormats = SupportedOutputFormats;
+
+    fn name(&self) -> Result<String, DeviceNameError> {
+        Device::name(self)
+    }
+
+    fn supported_input_formats(&self) -> Result<Self::SupportedInputFormats, SupportedFormatsError> {
+        Device::supported_input_formats(self)
+    }
+
+    fn supported_output_formats(&self) -> Result<Self::SupportedOutputFormats, SupportedFormatsError> {
+        Device::supported_output_formats(self)
+    }
+
+    fn default_input_format(&self) -> Result<Format, DefaultFormatError> {
+        Device::default_input_format(self)
+    }
+
+    fn default_output_format(&self) -> Result<Format, DefaultFormatError> {
+        Device::default_output_format(self)
+    }
+}
+
+impl EventLoopTrait for EventLoop {
+    type Device = Device;
+    type StreamId = StreamId;
+
+    fn build_input_stream(
+        &self,
+        device: &Self::Device,
+        format: &Format,
+    ) -> Result<Self::StreamId, BuildStreamError> {
+        EventLoop::build_input_stream(self, device, format)
+    }
+
+    fn build_output_stream(
+        &self,
+        device: &Self::Device,
+        format: &Format,
+    ) -> Result<Self::StreamId, BuildStreamError> {
+        EventLoop::build_output_stream(self, device, format)
+    }
+
+    fn play_stream(&self, stream: Self::StreamId) -> Result<(), PlayStreamError> {
+        EventLoop::play_stream(self, stream)
+    }
+
+    fn pause_stream(&self, stream: Self::StreamId) -> Result<(), PauseStreamError> {
+        EventLoop::pause_stream(self, stream)
+    }
+
+    fn destroy_stream(&self, stream: Self::StreamId) {
+        EventLoop::destroy_stream(self, stream)
+    }
+
+    fn run<F>(&self, callback: F) -> !
+    where
+        F: FnMut(Self::StreamId, StreamDataResult) + Send,
+    {
+        EventLoop::run(self, callback)
+    }
+}
+
+impl StreamIdTrait for StreamId {}
diff --git a/src/platform/windows/asio/stream.rs b/src/host/asio/stream.rs
similarity index 93%
rename from src/platform/windows/asio/stream.rs
rename to src/host/asio/stream.rs
index d852d0a..2beb37d 100644
--- a/src/platform/windows/asio/stream.rs
+++ b/src/host/asio/stream.rs
@@ -10,10 +10,13 @@ use std::sync::atomic::{AtomicUsize, Ordering};
 use std::sync::{Arc, Mutex};
 use std::thread;
 use std::time::Duration;
-use CreationError;
+use BuildStreamError;
 use Format;
+use PauseStreamError;
+use PlayStreamError;
 use SampleFormat;
 use StreamData;
+use StreamDataResult;
 use UnknownTypeInputBuffer;
 use UnknownTypeOutputBuffer;
 
@@ -26,7 +29,7 @@ pub struct EventLoop {
     /// Total stream count
     stream_count: AtomicUsize,
     /// The CPAL callback that the user gives to fill the buffers.
-    callbacks: Arc<Mutex<Option<&'static mut (FnMut(StreamId, StreamData) + Send)>>>,
+    callbacks: Arc<Mutex<Option<&'static mut (FnMut(StreamId, StreamDataResult) + Send)>>>,
 }
 
 /// Id for each stream.
@@ -35,13 +38,6 @@ pub struct EventLoop {
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct StreamId(usize);
 
-pub struct InputBuffer<'a, T: 'a> {
-    buffer: &'a [T],
-}
-pub struct OutputBuffer<'a, T: 'a> {
-    buffer: &'a mut [T],
-}
-
 /// CPAL stream.
 /// This decouples the many cpal streams
 /// from the single input and single output
@@ -92,8 +88,8 @@ impl EventLoop {
         &self,
         drivers: &sys::Drivers,
         format: &Format,
-        num_asio_channels: u16, 
-    ) -> Result<(), CreationError> {
+        num_asio_channels: u16,
+    ) -> Result<(), BuildStreamError> {
         let Format {
             channels,
             sample_rate,
@@ -107,16 +103,16 @@ impl EventLoop {
                     .set_sample_rate(sample_rate)
                     .expect("Unsupported sample rate");
             } else {
-                return Err(CreationError::FormatNotSupported);
+                return Err(BuildStreamError::FormatNotSupported);
             }
         }
         // unsigned formats are not supported by asio
         match data_type {
             SampleFormat::I16 | SampleFormat::F32 => (),
-            SampleFormat::U16 => return Err(CreationError::FormatNotSupported),
+            SampleFormat::U16 => return Err(BuildStreamError::FormatNotSupported),
         }
         if *channels > num_asio_channels {
-            return Err(CreationError::FormatNotSupported);
+            return Err(BuildStreamError::FormatNotSupported);
         }
         Ok(())
     }
@@ -129,13 +125,13 @@ impl EventLoop {
         drivers: &sys::Drivers,
         format: &Format,
         device: &Device,
-    ) -> Result<usize, CreationError> {
+    ) -> Result<usize, BuildStreamError> {
         match device.default_input_format() {
             Ok(f) => {
                 let num_asio_channels = f.channels;
                 self.check_format(drivers, format, num_asio_channels)
             },
-            Err(_) => Err(CreationError::FormatNotSupported),
+            Err(_) => Err(BuildStreamError::FormatNotSupported),
         }?;
         let num_channels = format.channels as usize;
         let ref mut streams = *self.asio_streams.lock().unwrap();
@@ -156,7 +152,7 @@ impl EventLoop {
                         bs
                     }).map_err(|ref e| {
                         println!("Error preparing stream: {}", e);
-                        CreationError::DeviceNotAvailable
+                        BuildStreamError::DeviceNotAvailable
                     })
             }
         }
@@ -170,13 +166,13 @@ impl EventLoop {
         drivers: &sys::Drivers,
         format: &Format,
         device: &Device,
-    ) -> Result<usize, CreationError> {
+    ) -> Result<usize, BuildStreamError> {
         match device.default_output_format() {
             Ok(f) => {
                 let num_asio_channels = f.channels;
                 self.check_format(drivers, format, num_asio_channels)
             },
-            Err(_) => Err(CreationError::FormatNotSupported),
+            Err(_) => Err(BuildStreamError::FormatNotSupported),
         }?;
         let num_channels = format.channels as usize;
         let ref mut streams = *self.asio_streams.lock().unwrap();
@@ -197,18 +193,18 @@ impl EventLoop {
                         bs
                     }).map_err(|ref e| {
                         println!("Error preparing stream: {}", e);
-                        CreationError::DeviceNotAvailable
+                        BuildStreamError::DeviceNotAvailable
                     })
             }
         }
     }
 
-    /// Builds a new cpal input stream  
+    /// Builds a new cpal input stream
     pub fn build_input_stream(
         &self,
         device: &Device,
         format: &Format,
-    ) -> Result<StreamId, CreationError> {
+    ) -> Result<StreamId, BuildStreamError> {
         let Device { drivers, .. } = device;
         let num_channels = format.channels.clone();
         let stream_type = drivers.get_data_type().expect("Couldn't load data type");
@@ -328,7 +324,7 @@ impl EventLoop {
                     $SampleTypeIdent:ident,
                     $Sample:expr
                     ) => {
-                        (*$Sample as f64 * ::std::$SampleTypeIdent::MAX as f64) as $SampleType 
+                        (*$Sample as f64 * ::std::$SampleTypeIdent::MAX as f64) as $SampleType
                     };
                     (f64,
                     $SampleType:ty,
@@ -396,18 +392,14 @@ impl EventLoop {
                             }
                         }
 
-                        // Wrap the buffer in the CPAL type
-                        let buff = InputBuffer {
-                            buffer: &mut $Buffers.cpal,
-                        };
                         // Call the users callback with the buffer
                         callback(
                             StreamId(count),
-                            StreamData::Input {
+                            Ok(StreamData::Input {
                                 buffer: UnknownTypeInputBuffer::$SampleFormat(::InputBuffer {
-                                    buffer: Some(super::super::InputBuffer::Asio(buff)),
+                                    buffer: &$Buffers.cpal,
                                 }),
-                            },
+                            }),
                         );
                     };
                 };
@@ -542,7 +534,7 @@ impl EventLoop {
         &self,
         device: &Device,
         format: &Format,
-    ) -> Result<StreamId, CreationError> {
+    ) -> Result<StreamId, BuildStreamError> {
         let Device { drivers, .. } = device;
         let num_channels = format.channels.clone();
         let stream_type = drivers.get_data_type().expect("Couldn't load data type");
@@ -626,28 +618,28 @@ impl EventLoop {
                     f32,
                     $Sample:expr
                     ) => {
-                        *$Sample as f64 
+                        *$Sample as f64
                     };
                     ($AsioTypeIdent:ident,
                     f32,
                     f64,
                     $Sample:expr
                     ) => {
-                        *$Sample as f32 
+                        *$Sample as f32
                     };
                     ($AsioTypeIdent:ident,
                     $AsioType:ty,
                     f32,
                     $Sample:expr
                     ) => {
-                        (*$Sample as f64 * ::std::$AsioTypeIdent::MAX as f64) as $AsioType 
+                        (*$Sample as f64 * ::std::$AsioTypeIdent::MAX as f64) as $AsioType
                     };
                     ($AsioTypeIdent:ident,
                     $AsioType:ty,
                     f64,
                     $Sample:expr
                     ) => {
-                        (*$Sample as f64 * ::std::$AsioTypeIdent::MAX as f64) as $AsioType 
+                        (*$Sample as f64 * ::std::$AsioTypeIdent::MAX as f64) as $AsioType
                     };
                     ($AsioTypeIdent:ident,
                     f32,
@@ -695,15 +687,13 @@ impl EventLoop {
                             // users data
                             callback(
                                 StreamId(count),
-                                StreamData::Output {
+                                Ok(StreamData::Output {
                                     buffer: UnknownTypeOutputBuffer::$SampleFormat(
                                         ::OutputBuffer {
-                                            target: Some(super::super::OutputBuffer::Asio(
-                                                buff,
-                                            )),
+                                            buffer: &mut my_buffers.cpal,
                                         },
                                     ),
-                                },
+                                }),
                             );
                         }
                         // Deinter all the channels
@@ -897,7 +887,7 @@ impl EventLoop {
 
     /// Play the cpal stream for the given ID.
     /// Also play The ASIO streams if they are not already.
-    pub fn play_stream(&self, stream_id: StreamId) {
+    pub fn play_stream(&self, stream_id: StreamId) -> Result<(), PlayStreamError> {
         let mut streams = self.cpal_streams.lock().unwrap();
         if let Some(s) = streams.get_mut(stream_id.0).expect("Bad play stream index") {
             s.playing = true;
@@ -908,7 +898,7 @@ impl EventLoop {
 
     /// Pause the cpal stream for the given ID.
     /// Pause the ASIO streams if there are no CPAL streams palying.
-    pub fn pause_stream(&self, stream_id: StreamId) {
+    pub fn pause_stream(&self, stream_id: StreamId) -> Result<(), PauseStreamError> {
         let mut streams = self.cpal_streams.lock().unwrap();
         if let Some(s) = streams
             .get_mut(stream_id.0)
@@ -933,9 +923,9 @@ impl EventLoop {
     /// Run the cpal callbacks
     pub fn run<F>(&self, mut callback: F) -> !
     where
-        F: FnMut(StreamId, StreamData) + Send,
+        F: FnMut(StreamId, StreamDataResult) + Send,
     {
-        let callback: &mut (FnMut(StreamId, StreamData) + Send) = &mut callback;
+        let callback: &mut (FnMut(StreamId, StreamDataResult) + Send) = &mut callback;
         // Transmute needed to convince the compiler that the callback has a static lifetime
         *self.callbacks.lock().unwrap() = Some(unsafe { mem::transmute(callback) });
         loop {
@@ -958,25 +948,6 @@ impl Drop for EventLoop {
     }
 }
 
-impl<'a, T> InputBuffer<'a, T> {
-    pub fn buffer(&self) -> &[T] {
-        &self.buffer
-    }
-    pub fn finish(self) {}
-}
-
-impl<'a, T> OutputBuffer<'a, T> {
-    pub fn buffer(&mut self) -> &mut [T] {
-        &mut self.buffer
-    }
-
-    pub fn len(&self) -> usize {
-        self.buffer.len()
-    }
-
-    pub fn finish(self) {}
-}
-
 /// Helper function to convert to system endianness
 fn convert_endian_to<T: PrimInt>(sample: T, endian: Endian) -> T {
     match endian {
diff --git a/src/host/mod.rs b/src/host/mod.rs
index 0c3155e..2bc9b2e 100644
--- a/src/host/mod.rs
+++ b/src/host/mod.rs
@@ -1,5 +1,7 @@
 #[cfg(any(target_os = "linux", target_os = "freebsd"))]
 pub(crate) mod alsa;
+#[cfg(windows)]
+pub(crate) mod asio;
 #[cfg(any(target_os = "macos", target_os = "ios"))]
 pub(crate) mod coreaudio;
 #[cfg(target_os = "emscripten")]
diff --git a/src/os/mod.rs b/src/os/mod.rs
deleted file mode 100644
index 3716caa..0000000
--- a/src/os/mod.rs
+++ /dev/null
@@ -1,7 +0,0 @@
-/// The cpal::os module provides operating-system-specific 
-/// functionality. If you are using this module within a 
-/// cross-platform project, you may wish to use 
-/// cfg(target_os = "<os_name>") to ensure that you only 
-/// use the OS-specific items when compiling for that OS.
-#[cfg(target_os = "windows")]
-pub mod windows;
diff --git a/src/os/windows/mod.rs b/src/os/windows/mod.rs
deleted file mode 100644
index e148c81..0000000
--- a/src/os/windows/mod.rs
+++ /dev/null
@@ -1,36 +0,0 @@
-/// This allows you to choose either Wasapi or ASIO 
-/// as your back end. Wasapi is the default.
-/// The CPAL_ASIO_DIR must be set to the ASIO SDK
-/// directory for use_asio_backend to be available. 
-use std::sync::Mutex;
-
-#[derive(Clone)]
-pub enum BackEnd {
-    Wasapi,
-    Asio,
-}
-
-lazy_static! {
-    static ref BACK_END: Mutex<BackEnd> = Mutex::new(BackEnd::Wasapi);
-}
-
-/// See which beackend is currently set.
-pub fn which_backend() -> BackEnd {
-    (*BACK_END.lock().unwrap()).clone()
-}
-
-#[cfg(asio)]
-/// Choose ASIO as the backend 
-pub fn use_asio_backend() -> Result<(), BackEndError> {
-    *BACK_END.lock().unwrap() = BackEnd::Asio;
-    Ok(())
-}
-
-/// Choose Wasapi as the backend 
-pub fn use_wasapi_backend() -> Result<(), BackEndError> {
-    *BACK_END.lock().unwrap() = BackEnd::Wasapi;
-    Ok(())
-}
-
-#[derive(Debug)]
-pub struct BackEndError;
\ No newline at end of file
diff --git a/src/platform/mod.rs b/src/platform/mod.rs
index 74030a5..f97697e 100644
--- a/src/platform/mod.rs
+++ b/src/platform/mod.rs
@@ -516,6 +516,15 @@ mod platform_impl {
 // TODO: Add `Asio asio` once #221 lands.
 #[cfg(windows)]
 mod platform_impl {
+    pub use crate::host::asio::{
+        Device as AsioDevice,
+        Devices as AsioDevices,
+        EventLoop as AsioEventLoop,
+        Host as AsioHost,
+        StreamId as AsioStreamId,
+        SupportedInputFormats as AsioSupportedInputFormats,
+        SupportedOutputFormats as AsioSupportedOutputFormats,
+    };
     pub use crate::host::wasapi::{
         Device as WasapiDevice,
         Devices as WasapiDevices,
@@ -526,7 +535,7 @@ mod platform_impl {
         SupportedOutputFormats as WasapiSupportedOutputFormats,
     };
 
-    impl_platform_host!(Wasapi wasapi);
+    impl_platform_host!(Asio asio, Wasapi wasapi);
 
     /// The default host for the current compilation target platform.
     pub fn default_host() -> Host {
diff --git a/src/platform/windows/asio/mod.rs b/src/platform/windows/asio/mod.rs
deleted file mode 100644
index 1d49f42..0000000
--- a/src/platform/windows/asio/mod.rs
+++ /dev/null
@@ -1,9 +0,0 @@
-extern crate asio_sys as sys;
-
-pub use self::device::{Device, Devices, SupportedInputFormats, SupportedOutputFormats, default_input_device, default_output_device};
-
-pub use self::stream::{InputBuffer, OutputBuffer, EventLoop, StreamId};
-
-mod device;
-mod stream;
-mod asio_utils;
\ No newline at end of file
diff --git a/src/platform/windows/mod.rs b/src/platform/windows/mod.rs
deleted file mode 100644
index b274ec0..0000000
--- a/src/platform/windows/mod.rs
+++ /dev/null
@@ -1,2 +0,0 @@
-#[cfg(windows)]
-mod asio;