diff --git a/YampaSynth.cabal b/YampaSynth.cabal
--- a/YampaSynth.cabal
+++ b/YampaSynth.cabal
@@ -1,5 +1,5 @@
 name: YampaSynth
-version: 0.0.1
+version: 0.0.2
 cabal-Version: >= 1.2
 license: BSD3
 license-file: LICENSE
@@ -41,31 +41,31 @@
 
 executable yampasynth-wav
   if flag (wav)
-    build-depends: base, array, bytestring, containers, Yampa, HCodecs
+    build-depends: base < 5, array, bytestring, containers, Yampa, HCodecs
   else
     buildable: False
   hs-source-dirs: src
   main-is: Main/Wav.hs
   other-modules: SynthBasics, SynthParams, MidiSynth, Player.Wav  
-  ghc-options: -O2 -Wall
+  ghc-options: -O3 -Wall
   
 executable yampasynth-openal
   if flag (openal)
-    build-Depends: base, array, containers, OpenAL, Yampa, HCodecs
+    build-Depends: base < 5, array, containers, OpenAL, Yampa, HCodecs
   else
     buildable: False
   hs-source-dirs:  src
   main-is: Main/OpenAL.hs
   other-modules: SynthBasics, SynthParams, MidiSynth, Player.OpenAL
-  ghc-options: -threaded -O2 -Wall
+  ghc-options: -threaded -O3 -Wall
 
 executable yampasynth-gtk
   if flag (gtk)
-    build-Depends: base, array, containers, OpenAL, glade, gtk, Yampa, HCodecs  
+    build-Depends: base < 5, array, containers, OpenAL, glade, gtk, Yampa, HCodecs  
   else
     buildable: False
   hs-source-dirs:  src
   main-is: Main/Gtk.hs
   other-modules: SynthBasics, SynthParams, MidiSynth, Player.OpenAL, Player.Gtk
-  ghc-options: -threaded -O2 -Wall
+  ghc-options: -threaded -O3 -Wall
 
diff --git a/src/Main/OpenAL.hs b/src/Main/OpenAL.hs
--- a/src/Main/OpenAL.hs
+++ b/src/Main/OpenAL.hs
@@ -8,9 +8,7 @@
 
 import FRP.Yampa
 
-import Data.Char
 import Numeric
-import Control.Monad
 import System.IO
 import System.Environment
 import System.Console.GetOpt
@@ -44,23 +42,23 @@
         return (sr, sf, mf)
       _ -> fail $ usageInfo "all options are mandatory\n" options
 
-  putStrLn "Importing MIDI File ..."
+  hPutStrLn stderr "Importing MIDI File ..."
   eMidi <- Midi.importFile midiFile
   midi <- case  eMidi of
     Left err -> fail err
     Right midi -> return midi
-  putStrLn "Done."
+  hPutStrLn stderr "Done."
   
-  putStrLn "Importing SoundFontFile ... This may take a while ..."
+  hPutStrLn stderr "Importing SoundFontFile ... This may take a while ..."
   eSoundFont <- SF.importFile soundFontFile
   soundFont <- case  eSoundFont of
     Left err -> fail err
     Right sf -> return sf
-  putStrLn "Done."
+  hPutStrLn stderr "Done."
   
-  putStrLn "Now you should hear something ..."
-  putStrLn "If you are getting interruptions decrase sampling rate."
+  hPutStrLn stderr "Now you should hear something ..."
+  hPutStrLn stderr "If you are getting interruptions decrase sampling rate."
   let paramsGen = soundFontToSynthParams soundFont
       signalFunction = midiToEventSource midi >>> midiSynth paramsGen
   Player.OpenAL.play sampleRate' (256 * 1024) signalFunction
-  putStrLn "Done."
+  hPutStrLn stderr "Done."
diff --git a/src/Main/Wav.hs b/src/Main/Wav.hs
--- a/src/Main/Wav.hs
+++ b/src/Main/Wav.hs
@@ -8,9 +8,7 @@
 
 import FRP.Yampa
 
-import Data.Char
 import Numeric
-import Control.Monad
 import System.IO
 import System.Environment
 import System.Console.GetOpt
@@ -31,7 +29,7 @@
  , Option ['m'] ["midi"]       (ReqArg MidiFile "FILE")
    "midi FILE to synthesize"
  , Option ['o'] ["output"]     (ReqArg Output "FILE")
-   "output FILE (.wav file), if FILE argument ommited audio will be sent to sound card in real-time"
+   "output FILE (.wav file), if FILE argument equals stdout then the output will be sent to standard output. The output can be piped to an audio/video player (e.g., mplayer)"
  ]
 
 main :: IO ()
@@ -46,22 +44,22 @@
         return (sr, sf, mf, wf)
       _ -> fail $ usageInfo "all options are mandatory\n" options
 
-  putStrLn "Importing MIDI File ..."
+  hPutStrLn stderr "Importing MIDI File ..."
   eMidi <- Midi.importFile midiFile
   midi <- case  eMidi of
     Left err -> fail err
     Right midi -> return midi
-  putStrLn "Done."
+  hPutStrLn stderr "Done."
   
-  putStrLn "Importing SoundFontFile ... This may take a while ..."
+  hPutStrLn stderr "Importing SoundFontFile ... This may take a while ..."
   eSoundFont <- SF.importFile soundFontFile
   soundFont <- case  eSoundFont of
     Left err -> fail err
     Right sf -> return sf
-  putStrLn "Done."
+  hPutStrLn stderr "Done."
   
-  putStrLn $ "Writing WAV audio data to '" ++ wavFile  ++ "' ..."
+  hPutStrLn stderr $ "Writing WAV audio data to '" ++ wavFile  ++ "' ..."
   let paramsGen = soundFontToSynthParams soundFont
       sf = midiToEventSource midi >>> midiSynth paramsGen
   Player.Wav.play wavFile sampleRate' sf
-  putStrLn "Done."
+  hPutStrLn stderr "Done."
diff --git a/src/Player/OpenAL.hs b/src/Player/OpenAL.hs
--- a/src/Player/OpenAL.hs
+++ b/src/Player/OpenAL.hs
@@ -12,20 +12,17 @@
 
 import Sound.OpenAL 
 
-import Data.Maybe
 import Data.Int
 import Data.IORef
-import Control.Monad
 import Foreign.Storable
 import Foreign.Marshal.Alloc
-import Foreign.Storable
 import Foreign.Ptr
 import Control.Concurrent  
 
 play ::Int -> Int -> SF () (Sample, Event ()) -> IO ()
 play sampleRate' sampleNumber' sf = do
   mVarEnd <- newEmptyMVar
-  forkIO $ (play' sampleRate' sampleNumber' sf) >> putMVar mVarEnd ()
+  _ <- forkIO $ (play' sampleRate' sampleNumber' sf) >> putMVar mVarEnd ()
   takeMVar mVarEnd
   return ()
 
@@ -36,7 +33,7 @@
   mVarMaybeChunk <- newEmptyMVar
   mVarReply <- newEmptyMVar
   
-  forkIO $ process sampleRate' pSource pBuffer mVarMaybeChunk mVarReply
+  _ <- forkIO $ process sampleRate' pSource pBuffer mVarMaybeChunk mVarReply
 
   ir <- newIORef (0 :: Int)
   let sampleSize = sizeOf (undefined :: Int16)
@@ -78,13 +75,7 @@
   case mDevice of
     Nothing -> fail "opening OpenAL device"
     Just device -> do
-      mContext <- createContext device [
---            Frequency (fromIntegral 44100)
---          , Refresh (fromIntegral 44101)
---          Frequency (fromIntegral sampleRate)
---        , MonoSources 1
---        , StereoSources 0
-        ]
+      mContext <- createContext device []
       case mContext of 
         Nothing -> fail "opening OpenAL context"
         Just context -> do
diff --git a/src/Player/Wav.hs b/src/Player/Wav.hs
--- a/src/Player/Wav.hs
+++ b/src/Player/Wav.hs
@@ -13,7 +13,9 @@
 
 play :: FilePath -> Int -> SF () (Sample, Event ()) -> IO ()
 play filePath sampleRate' signalFunction = do
-  h <- openFile filePath WriteMode
+  h <- case filePath of
+         "stdout" -> return stdout
+         _        -> openFile filePath WriteMode
   hSetBuffering h (BlockBuffering (Just 1024))
   let a = Audio {
         sampleRate = sampleRate'