diff --git a/Makefile.am b/Makefile.am
index 05eab64..6b7aca7 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -9,8 +9,8 @@ lib_LTLIBRARIES = %D%/librtaudio.la
 %C%_librtaudio_la_CXXFLAGS = -DRTAUDIO_EXPORT
 %C%_librtaudio_la_LDFLAGS = -no-undefined -export-dynamic -version-info @SO_VERSION@
 %C%_librtaudio_la_SOURCES = \
-  %D%/RtAudio.cpp \
-  %D%/rtaudio_c.cpp
+  %D%/RtAudio.cpp
+#  %D%/rtaudio_c.cpp
 
 if ASIO
 %C%_librtaudio_la_SOURCES += \
diff --git a/RtAudio.cpp b/RtAudio.cpp
index e147b36..5d1b5b8 100644
--- a/RtAudio.cpp
+++ b/RtAudio.cpp
@@ -39,7 +39,7 @@
 */
 /************************************************************************/
 
-// RtAudio: Version 5.1.0
+// RtAudio: Version 6.0.0beta1
 
 #include "RtAudio.h"
 #include <iostream>
@@ -264,9 +264,9 @@ RtAudio :: RtAudio( RtAudio::Api api )
   // It should not be possible to get here because the preprocessor
   // definition __RTAUDIO_DUMMY__ is automatically defined in RtAudio.h
   // if no API-specific definitions are passed to the compiler. But just
-  // in case something weird happens, we'll throw an error.
-  std::string errorText = "\nRtAudio: no compiled API support found ... critical error!!\n\n";
-  throw( RtAudioError( errorText, RtAudioError::UNSPECIFIED ) );
+  // in case something weird happens, issue an error message and abort.
+  std::cerr << "\nRtAudio: no compiled API support found ... critical error!\n" << std::endl;
+  abort();
 }
 
 RtAudio :: ~RtAudio()
@@ -275,17 +275,16 @@ RtAudio :: ~RtAudio()
     delete rtapi_;
 }
 
-//void RtAudio :: openStream( RtAudio::StreamParameters *outputParameters,
-RtAudioError::Type RtAudio :: openStream( RtAudio::StreamParameters *outputParameters,
+RtAudioErrorType RtAudio :: openStream( RtAudio::StreamParameters *outputParameters,
                                           RtAudio::StreamParameters *inputParameters,
                                           RtAudioFormat format, unsigned int sampleRate,
                                           unsigned int *bufferFrames,
                                           RtAudioCallback callback, void *userData,
-                                          RtAudio::StreamOptions *options ) //, RtAudioErrorCallback errorCallback )
+                                          RtAudio::StreamOptions *options )
 {
   return rtapi_->openStream( outputParameters, inputParameters, format,
                              sampleRate, bufferFrames, callback,
-                             userData, options ); //, errorCallback );
+                             userData, options );
 }
 
 // *************************************************** //
@@ -301,7 +300,6 @@ RtApi :: RtApi()
   MUTEX_INITIALIZE( &stream_.mutex );
   errorCallback_ = 0;
   showWarnings_ = true;
-  //firstErrorOccurred_ = false;
 }
 
 RtApi :: ~RtApi()
@@ -309,19 +307,16 @@ RtApi :: ~RtApi()
   MUTEX_DESTROY( &stream_.mutex );
 }
 
-//void RtApi :: openStream( RtAudio::StreamParameters *oParams,
-RtAudioError::Type RtApi :: openStream( RtAudio::StreamParameters *oParams,
+RtAudioErrorType RtApi :: openStream( RtAudio::StreamParameters *oParams,
                                         RtAudio::StreamParameters *iParams,
                                         RtAudioFormat format, unsigned int sampleRate,
                                         unsigned int *bufferFrames,
                                         RtAudioCallback callback, void *userData,
-                                        RtAudio::StreamOptions *options ) //, RtAudioErrorCallback errorCallback )
+                                        RtAudio::StreamOptions *options )
 {
-  //RtAudioError::Type type = RtAudioError::NO_ERROR;
   if ( stream_.state != STREAM_CLOSED ) {
-    //type = RtAudioError::INVALID_USE;
     errorText_ = "RtApi::openStream: a stream is already open!";
-    return error( RtAudioError::INVALID_USE );
+    return error( RTAUDIO_INVALID_USE );
   }
 
   // Clear stream information potentially left from a previously open stream.
@@ -329,26 +324,22 @@ RtAudioError::Type RtApi :: openStream( RtAudio::StreamParameters *oParams,
 
   if ( oParams && oParams->nChannels < 1 ) {
     errorText_ = "RtApi::openStream: a non-NULL output StreamParameters structure cannot have an nChannels value less than one.";
-    return error( RtAudioError::INVALID_USE );
-    //return;
+    return error( RTAUDIO_INVALID_USE );
   }
 
   if ( iParams && iParams->nChannels < 1 ) {
     errorText_ = "RtApi::openStream: a non-NULL input StreamParameters structure cannot have an nChannels value less than one.";
-    return error( RtAudioError::INVALID_USE );
-    //return;
+    return error( RTAUDIO_INVALID_USE );
   }
 
   if ( oParams == NULL && iParams == NULL ) {
     errorText_ = "RtApi::openStream: input and output StreamParameters structures are both NULL!";
-    return error( RtAudioError::INVALID_USE );
-    //return;
+    return error( RTAUDIO_INVALID_USE );
   }
 
   if ( formatBytes(format) == 0 ) {
     errorText_ = "RtApi::openStream: 'format' parameter value is undefined.";
-    return error( RtAudioError::INVALID_USE );
-    //return;
+    return error( RTAUDIO_INVALID_USE );
   }
 
   unsigned int nDevices = getDeviceCount();
@@ -357,8 +348,7 @@ RtAudioError::Type RtApi :: openStream( RtAudio::StreamParameters *oParams,
     oChannels = oParams->nChannels;
     if ( oParams->deviceId >= nDevices ) {
       errorText_ = "RtApi::openStream: output device parameter value is invalid.";
-      return error( RtAudioError::INVALID_USE );
-      //return;
+      return error( RTAUDIO_INVALID_USE );
     }
   }
 
@@ -367,8 +357,7 @@ RtAudioError::Type RtApi :: openStream( RtAudio::StreamParameters *oParams,
     iChannels = iParams->nChannels;
     if ( iParams->deviceId >= nDevices ) {
       errorText_ = "RtApi::openStream: input device parameter value is invalid.";
-      return error( RtAudioError::INVALID_USE );
-      //return;
+      return error( RTAUDIO_INVALID_USE );
     }
   }
 
@@ -379,8 +368,7 @@ RtAudioError::Type RtApi :: openStream( RtAudio::StreamParameters *oParams,
     result = probeDeviceOpen( oParams->deviceId, OUTPUT, oChannels, oParams->firstChannel,
                               sampleRate, format, bufferFrames, options );
     if ( result == false ) {
-      return error( RtAudioError::SYSTEM_ERROR );
-      //return;
+      return error( RTAUDIO_SYSTEM_ERROR );
     }
   }
 
@@ -390,18 +378,16 @@ RtAudioError::Type RtApi :: openStream( RtAudio::StreamParameters *oParams,
                               sampleRate, format, bufferFrames, options );
     if ( result == false ) {
       if ( oChannels > 0 ) closeStream();
-      return error( RtAudioError::SYSTEM_ERROR );
-      //return;
+      return error( RTAUDIO_SYSTEM_ERROR );
     }
   }
 
   stream_.callbackInfo.callback = (void *) callback;
   stream_.callbackInfo.userData = userData;
-  //stream_.callbackInfo.errorCallback = (void *) errorCallback;
 
   if ( options ) options->numberOfBuffers = stream_.nBuffers;
   stream_.state = STREAM_STOPPED;
-  return RtAudioError::NO_ERROR;
+  return RTAUDIO_NO_ERROR;
 }
 
 unsigned int RtApi :: getDefaultInputDevice( void )
@@ -482,8 +468,6 @@ double RtApi :: getStreamTime( void )
 
 void RtApi :: setStreamTime( double time )
 {
-  //  verifyStream();
-
   if ( time >= 0.0 )
     stream_.streamTime = time;
   /*
@@ -495,7 +479,6 @@ void RtApi :: setStreamTime( double time )
 
 unsigned int RtApi :: getStreamSampleRate( void )
 {
-  //verifyStream();
   if ( isStreamOpen() ) return stream_.sampleRate;
   else return 0;
 }
@@ -557,7 +540,7 @@ RtApiCore:: RtApiCore()
   OSStatus result = AudioObjectSetPropertyData( kAudioObjectSystemObject, &property, 0, NULL, sizeof(CFRunLoopRef), &theRunLoop);
   if ( result != noErr ) {
     errorText_ = "RtApiCore::RtApiCore: error setting run loop property!";
-    error( RtAudioError::WARNING );
+    error( RTAUDIO_SYSTEM_ERROR );
   }
 #endif
 }
@@ -578,7 +561,7 @@ unsigned int RtApiCore :: getDeviceCount( void )
   OSStatus result = AudioObjectGetPropertyDataSize( kAudioObjectSystemObject, &propertyAddress, 0, NULL, &dataSize );
   if ( result != noErr ) {
     errorText_ = "RtApiCore::getDeviceCount: OS-X error getting device info!";
-    error( RtAudioError::WARNING );
+    error( RTAUDIO_SYSTEM_ERROR );
     return 0;
   }
 
@@ -596,7 +579,7 @@ unsigned int RtApiCore :: getDefaultInputDevice( void )
   OSStatus result = AudioObjectGetPropertyData( kAudioObjectSystemObject, &property, 0, NULL, &dataSize, &id );
   if ( result != noErr ) {
     errorText_ = "RtApiCore::getDefaultInputDevice: OS-X system error getting device.";
-    error( RtAudioError::WARNING );
+    error( RTAUDIO_SYSTEM_ERROR );
     return 0;
   }
 
@@ -606,7 +589,7 @@ unsigned int RtApiCore :: getDefaultInputDevice( void )
   result = AudioObjectGetPropertyData( kAudioObjectSystemObject, &property, 0, NULL, &dataSize, (void *) &deviceList );
   if ( result != noErr ) {
     errorText_ = "RtApiCore::getDefaultInputDevice: OS-X system error getting device IDs.";
-    error( RtAudioError::WARNING );
+    error( RTAUDIO_SYSTEM_ERROR );
     return 0;
   }
 
@@ -614,7 +597,7 @@ unsigned int RtApiCore :: getDefaultInputDevice( void )
     if ( id == deviceList[i] ) return i;
 
   errorText_ = "RtApiCore::getDefaultInputDevice: No default device found!";
-  error( RtAudioError::WARNING );
+  error( RTAUDIO_WARNING );
   return 0;
 }
 
@@ -629,7 +612,7 @@ unsigned int RtApiCore :: getDefaultOutputDevice( void )
   OSStatus result = AudioObjectGetPropertyData( kAudioObjectSystemObject, &property, 0, NULL, &dataSize, &id );
   if ( result != noErr ) {
     errorText_ = "RtApiCore::getDefaultOutputDevice: OS-X system error getting device.";
-    error( RtAudioError::WARNING );
+    error( RTAUDIO_SYSTEM_ERROR );
     return 0;
   }
 
@@ -639,7 +622,7 @@ unsigned int RtApiCore :: getDefaultOutputDevice( void )
   result = AudioObjectGetPropertyData( kAudioObjectSystemObject, &property, 0, NULL, &dataSize, (void *) &deviceList );
   if ( result != noErr ) {
     errorText_ = "RtApiCore::getDefaultOutputDevice: OS-X system error getting device IDs.";
-    error( RtAudioError::WARNING );
+    error( RTAUDIO_SYSTEM_ERROR );
     return 0;
   }
 
@@ -647,7 +630,7 @@ unsigned int RtApiCore :: getDefaultOutputDevice( void )
     if ( id == deviceList[i] ) return i;
 
   errorText_ = "RtApiCore::getDefaultOutputDevice: No default device found!";
-  error( RtAudioError::WARNING );
+  error( RTAUDIO_WARNING );
   return 0;
 }
 
@@ -660,13 +643,13 @@ RtAudio::DeviceInfo RtApiCore :: getDeviceInfo( unsigned int device )
   unsigned int nDevices = getDeviceCount();
   if ( nDevices == 0 ) {
     errorText_ = "RtApiCore::getDeviceInfo: no devices found!";
-    error( RtAudioError::INVALID_USE );
+    error( RTAUDIO_INVALID_USE );
     return info;
   }
 
   if ( device >= nDevices ) {
     errorText_ = "RtApiCore::getDeviceInfo: device ID is invalid!";
-    error( RtAudioError::INVALID_USE );
+    error( RTAUDIO_INVALID_USE );
     return info;
   }
 
@@ -679,7 +662,7 @@ RtAudio::DeviceInfo RtApiCore :: getDeviceInfo( unsigned int device )
                                                 0, NULL, &dataSize, (void *) &deviceList );
   if ( result != noErr ) {
     errorText_ = "RtApiCore::getDeviceInfo: OS-X system error getting device IDs.";
-    error( RtAudioError::WARNING );
+    error( RTAUDIO_WARNING );
     return info;
   }
 
@@ -694,7 +677,7 @@ RtAudio::DeviceInfo RtApiCore :: getDeviceInfo( unsigned int device )
   if ( result != noErr ) {
     errorStream_ << "RtApiCore::probeDeviceInfo: system error (" << getErrorCode( result ) << ") getting device manufacturer.";
     errorText_ = errorStream_.str();
-    error( RtAudioError::WARNING );
+    error( RTAUDIO_WARNING );
     return info;
   }
 
@@ -716,7 +699,7 @@ RtAudio::DeviceInfo RtApiCore :: getDeviceInfo( unsigned int device )
   if ( result != noErr ) {
     errorStream_ << "RtApiCore::probeDeviceInfo: system error (" << getErrorCode( result ) << ") getting device name.";
     errorText_ = errorStream_.str();
-    error( RtAudioError::WARNING );
+    error( RTAUDIO_WARNING );
     return info;
   }
 
@@ -742,7 +725,7 @@ RtAudio::DeviceInfo RtApiCore :: getDeviceInfo( unsigned int device )
   if ( result != noErr || dataSize == 0 ) {
     errorStream_ << "RtApiCore::getDeviceInfo: system error (" << getErrorCode( result ) << ") getting output stream configuration info for device (" << device << ").";
     errorText_ = errorStream_.str();
-    error( RtAudioError::WARNING );
+    error( RTAUDIO_WARNING );
     return info;
   }
 
@@ -750,7 +733,7 @@ RtAudio::DeviceInfo RtApiCore :: getDeviceInfo( unsigned int device )
   bufferList = (AudioBufferList *) malloc( dataSize );
   if ( bufferList == NULL ) {
     errorText_ = "RtApiCore::getDeviceInfo: memory error allocating output AudioBufferList.";
-    error( RtAudioError::WARNING );
+    error( RTAUDIO_WARNING );
     return info;
   }
 
@@ -759,7 +742,7 @@ RtAudio::DeviceInfo RtApiCore :: getDeviceInfo( unsigned int device )
     free( bufferList );
     errorStream_ << "RtApiCore::getDeviceInfo: system error (" << getErrorCode( result ) << ") getting output stream configuration for device (" << device << ").";
     errorText_ = errorStream_.str();
-    error( RtAudioError::WARNING );
+    error( RTAUDIO_WARNING );
     return info;
   }
 
@@ -775,7 +758,7 @@ RtAudio::DeviceInfo RtApiCore :: getDeviceInfo( unsigned int device )
   if ( result != noErr || dataSize == 0 ) {
     errorStream_ << "RtApiCore::getDeviceInfo: system error (" << getErrorCode( result ) << ") getting input stream configuration info for device (" << device << ").";
     errorText_ = errorStream_.str();
-    error( RtAudioError::WARNING );
+    error( RTAUDIO_WARNING );
     return info;
   }
 
@@ -783,7 +766,7 @@ RtAudio::DeviceInfo RtApiCore :: getDeviceInfo( unsigned int device )
   bufferList = (AudioBufferList *) malloc( dataSize );
   if ( bufferList == NULL ) {
     errorText_ = "RtApiCore::getDeviceInfo: memory error allocating input AudioBufferList.";
-    error( RtAudioError::WARNING );
+    error( RTAUDIO_WARNING );
     return info;
   }
 
@@ -792,7 +775,7 @@ RtAudio::DeviceInfo RtApiCore :: getDeviceInfo( unsigned int device )
     free( bufferList );
     errorStream_ << "RtApiCore::getDeviceInfo: system error (" << getErrorCode( result ) << ") getting input stream configuration for device (" << device << ").";
     errorText_ = errorStream_.str();
-    error( RtAudioError::WARNING );
+    error( RTAUDIO_WARNING );
     return info;
   }
 
@@ -817,7 +800,7 @@ RtAudio::DeviceInfo RtApiCore :: getDeviceInfo( unsigned int device )
   if ( result != kAudioHardwareNoError || dataSize == 0 ) {
     errorStream_ << "RtApiCore::getDeviceInfo: system error (" << getErrorCode( result ) << ") getting sample rate info.";
     errorText_ = errorStream_.str();
-    error( RtAudioError::WARNING );
+    error( RTAUDIO_WARNING );
     return info;
   }
 
@@ -827,7 +810,7 @@ RtAudio::DeviceInfo RtApiCore :: getDeviceInfo( unsigned int device )
   if ( result != kAudioHardwareNoError ) {
     errorStream_ << "RtApiCore::getDeviceInfo: system error (" << getErrorCode( result ) << ") getting sample rates.";
     errorText_ = errorStream_.str();
-    error( RtAudioError::WARNING );
+    error( RTAUDIO_WARNING );
     return info;
   }
 
@@ -874,7 +857,7 @@ RtAudio::DeviceInfo RtApiCore :: getDeviceInfo( unsigned int device )
   if ( info.sampleRates.size() == 0 ) {
     errorStream_ << "RtApiCore::probeDeviceInfo: No supported sample rates found for device (" << device << ").";
     errorText_ = errorStream_.str();
-    error( RtAudioError::WARNING );
+    error( RTAUDIO_WARNING );
     return info;
   }
 
@@ -1299,7 +1282,7 @@ bool RtApiCore :: probeDeviceOpen( unsigned int device, StreamMode mode, unsigne
     else {
       errorStream_ << "RtApiCore::probeDeviceOpen: system error (" << getErrorCode( result ) << ") getting device latency for device (" << device << ").";
       errorText_ = errorStream_.str();
-      error( RtAudioError::WARNING );
+      error( RTAUDIO_WARNING );
     }
   }
 
@@ -1477,7 +1460,7 @@ void RtApiCore :: closeStream( void )
 {
   if ( stream_.state == STREAM_CLOSED ) {
     errorText_ = "RtApiCore::closeStream(): no open stream to close!";
-    error( RtAudioError::WARNING );
+    error( RTAUDIO_WARNING );
     return;
   }
 
@@ -1491,12 +1474,12 @@ void RtApiCore :: closeStream( void )
       property.mSelector = kAudioDeviceProcessorOverload;
       if (AudioObjectRemovePropertyListener( handle->id[0], &property, xrunListener, (void *) handle ) != noErr) {
         errorText_ = "RtApiCore::closeStream(): error removing xrun property listener!";
-        error( RtAudioError::WARNING );
+        error( RTAUDIO_WARNING );
       }
       property.mSelector = kAudioDevicePropertyDeviceIsAlive;
       if (AudioObjectRemovePropertyListener( handle->id[0], &property, disconnectListener, (void *) &stream_.callbackInfo ) != noErr) {
         errorText_ = "RtApiCore::closeStream(): error removing disconnect property listener!";
-        error( RtAudioError::WARNING );
+        error( RTAUDIO_WARNING );
       }
     }
     if ( stream_.state == STREAM_RUNNING )
@@ -1518,12 +1501,12 @@ void RtApiCore :: closeStream( void )
       property.mSelector = kAudioDeviceProcessorOverload;
       if (AudioObjectRemovePropertyListener( handle->id[1], &property, xrunListener, (void *) handle ) != noErr) {
         errorText_ = "RtApiCore::closeStream(): error removing xrun property listener!";
-        error( RtAudioError::WARNING );
+        error( RTAUDIO_WARNING );
       }
       property.mSelector = kAudioDevicePropertyDeviceIsAlive;
       if (AudioObjectRemovePropertyListener( handle->id[1], &property, disconnectListener, (void *) &stream_.callbackInfo ) != noErr) {
         errorText_ = "RtApiCore::closeStream(): error removing disconnect property listener!";
-        error( RtAudioError::WARNING );
+        error( RTAUDIO_WARNING );
       }
     }
     if ( stream_.state == STREAM_RUNNING )
@@ -1557,7 +1540,7 @@ void RtApiCore :: closeStream( void )
   CallbackInfo *info = (CallbackInfo *) &stream_.callbackInfo;
   if ( info->deviceDisconnected ) {
     errorText_ = "RtApiCore: the stream device was disconnected (and closed)!";
-    error( RtAudioError::DEVICE_DISCONNECT );
+    error( RTAUDIO_DEVICE_DISCONNECT );
   }
   
   clearStreamInfo();
@@ -1565,17 +1548,14 @@ void RtApiCore :: closeStream( void )
   //stream_.state = STREAM_CLOSED;
 }
 
-//void RtApiCore :: startStream( void )
-RtAudioError::Type RtApiCore :: startStream( void )
+RtAudioErrorType RtApiCore :: startStream( void )
 {
-  //verifyStream();
   if ( stream_.state != STREAM_STOPPED ) {
     if ( stream_.state == STREAM_RUNNING )
       errorText_ = "RtApiCore::startStream(): the stream is already running!";
     else if ( stream_.state == STREAM_STOPPING || stream_.state == STREAM_CLOSED )
       errorText_ = "RtApiCore::startStream(): the stream is stopping or closed!";
-    return error( RtAudioError::WARNING );
-    //return;
+    return error( RTAUDIO_WARNING );
   }
 
   /*
@@ -1612,27 +1592,23 @@ RtAudioError::Type RtApiCore :: startStream( void )
     }
   }
 
-  // set stream time to zero?
   handle->drainCounter = 0;
   handle->internalDrain = false;
   stream_.state = STREAM_RUNNING;
 
  unlock:
-  if ( result == noErr ) return RtAudioError::NO_ERROR;
-  return error( RtAudioError::SYSTEM_ERROR );
+  if ( result == noErr ) return RTAUDIO_NO_ERROR;
+  return error( RTAUDIO_SYSTEM_ERROR );
 }
 
-//void RtApiCore :: stopStream( void )
-RtAudioError::Type RtApiCore :: stopStream( void )
+RtAudioErrorType RtApiCore :: stopStream( void )
 {
-  //verifyStream();
   if ( stream_.state != STREAM_RUNNING && stream_.state != STREAM_STOPPING ) {
     if ( stream_.state == STREAM_STOPPED )
       errorText_ = "RtApiCore::stopStream(): the stream is already stopped!";
     else if ( stream_.state == STREAM_CLOSED )
       errorText_ = "RtApiCore::stopStream(): the stream is closed!";
-    return error( RtAudioError::WARNING );
-    //return;
+    return error( RTAUDIO_WARNING );
   }
 
   OSStatus result = noErr;
@@ -1665,20 +1641,18 @@ RtAudioError::Type RtApiCore :: stopStream( void )
   stream_.state = STREAM_STOPPED;
 
  unlock:
-  if ( result == noErr ) return RtAudioError::NO_ERROR;
-  return error( RtAudioError::SYSTEM_ERROR );
+  if ( result == noErr ) return RTAUDIO_NO_ERROR;
+  return error( RTAUDIO_SYSTEM_ERROR );
 }
 
-//void RtApiCore :: abortStream( void )
-RtAudioError::Type RtApiCore :: abortStream( void )
+RtAudioErrorType RtApiCore :: abortStream( void )
 {
-  //verifyStream();
   if ( stream_.state != STREAM_RUNNING ) {
     if ( stream_.state == STREAM_STOPPED )
       errorText_ = "RtApiCore::abortStream(): the stream is already stopped!";
     else if ( stream_.state == STREAM_STOPPING || stream_.state == STREAM_CLOSED )
       errorText_ = "RtApiCore::abortStream(): the stream is stopping or closed!";
-    return error( RtAudioError::WARNING );
+    return error( RTAUDIO_WARNING );
     //return;
   }
 
@@ -1710,7 +1684,7 @@ bool RtApiCore :: callbackEvent( AudioDeviceID deviceId,
   if ( stream_.state == STREAM_STOPPED || stream_.state == STREAM_STOPPING ) return SUCCESS;
   if ( stream_.state == STREAM_CLOSED ) {
     errorText_ = "RtApiCore::callbackEvent(): the stream is closed ... this shouldn't happen!";
-    error( RtAudioError::WARNING );
+    error( RTAUDIO_WARNING );
     return FAILURE;
   }
 
@@ -2119,7 +2093,7 @@ RtAudio::DeviceInfo RtApiJack :: getDeviceInfo( unsigned int device )
   jack_client_t *client = jack_client_open( "RtApiJackInfo", options, status );
   if ( client == 0 ) {
     errorText_ = "RtApiJack::getDeviceInfo: Jack server not found or connection error!";
-    error( RtAudioError::WARNING );
+    error( RTAUDIO_WARNING );
     return info;
   }
 
@@ -2623,7 +2597,7 @@ void RtApiJack :: startStream( void )
 
  unlock:
   if ( result == 0 ) return;
-  error( RtAudioError::SYSTEM_ERROR );
+  error( RtAudioError::RTAUDIO_SYSTEM_ERROR );
 }
 
 void RtApiJack :: stopStream( void )
@@ -9987,13 +9961,12 @@ static void *ossCallbackHandler( void *ptr )
 
 // This method can be modified to control the behavior of error
 // message printing.
-//void RtApi :: error( RtAudioError::Type type )
-RtAudioError::Type RtApi :: error( RtAudioError::Type type )
+RtAudioErrorType RtApi :: error( RtAudioErrorType type )
 {
   errorStream_.str(""); // clear the ostringstream to avoid repeated messages
 
   // Don't output warnings if showWarnings_ is false
-  if ( type == RtAudioError::WARNING && showWarnings_ == false ) return type;
+  if ( type == RTAUDIO_WARNING && showWarnings_ == false ) return type;
   
   if ( errorCallback_ ) {
     const std::string errorMessage = errorText_;
@@ -10029,7 +10002,6 @@ void RtApi :: clearStreamInfo()
   stream_.callbackInfo.callback = 0;
   stream_.callbackInfo.userData = 0;
   stream_.callbackInfo.isRunning = false;
-  //stream_.callbackInfo.errorCallback = 0;
   for ( int i=0; i<2; i++ ) {
     stream_.device[i] = 11111;
     stream_.doConvertBuffer[i] = false;
@@ -10065,7 +10037,7 @@ unsigned int RtApi :: formatBytes( RtAudioFormat format )
     return 1;
 
   errorText_ = "RtApi::formatBytes: undefined format.";
-  error( RtAudioError::WARNING );
+  error( RTAUDIO_WARNING );
 
   return 0;
 }
diff --git a/RtAudio.h b/RtAudio.h
index 9e02ed6..ca08bc4 100644
--- a/RtAudio.h
+++ b/RtAudio.h
@@ -46,7 +46,7 @@
 #ifndef __RTAUDIO_H
 #define __RTAUDIO_H
 
-#define RTAUDIO_VERSION "5.1.0"
+#define RTAUDIO_VERSION "6.0.0beta1"
 
 #if defined _WIN32 || defined __CYGWIN__
   #if defined(RTAUDIO_EXPORT)
@@ -64,7 +64,7 @@
 
 #include <string>
 #include <vector>
-#include <stdexcept>
+//#include <stdexcept>
 #include <iostream>
 
 /*! \typedef typedef unsigned long RtAudioFormat;
@@ -208,51 +208,65 @@ typedef int (*RtAudioCallback)( void *outputBuffer, void *inputBuffer,
 
 /************************************************************************/
 /*! \class RtAudioError
-    \brief Exception handling class for RtAudio.
+    \brief Error handling class for RtAudio.
 
     The RtAudioError class is quite simple but it does allow errors to be
-    "caught" by RtAudioError::Type. See the RtAudio documentation to know
-    which methods can throw an RtAudioError.
+    identified by RtAudioError::Type.
 */
 /************************************************************************/
 
-class RTAUDIO_DLL_PUBLIC RtAudioError : public std::runtime_error
-{
- public:
-  //! Defined RtAudioError types.
-  enum Type {
-    NO_ERROR,          /*!< No error. */
-    WARNING,           /*!< A non-critical error. */
-    UNSPECIFIED,       /*!< The default, unspecified error type. */
-    NO_DEVICES_FOUND,  /*!< No devices found on system. */
-    INVALID_DEVICE,    /*!< An invalid device ID was specified. */
-    DEVICE_DISCONNECT, /*!< A device in use was disconnected. */
-    MEMORY_ERROR,      /*!< An error occured during memory allocation. */
-    INVALID_PARAMETER, /*!< An invalid parameter was specified to a function. */
-    INVALID_USE,       /*!< The function was called incorrectly. */
-    DRIVER_ERROR,      /*!< A system driver error occured. */
-    SYSTEM_ERROR,      /*!< A system error occured. */
-    THREAD_ERROR       /*!< A thread error occured. */
-  };
-
-  //! The constructor.
-  RtAudioError( const std::string& message,
-                Type type = RtAudioError::UNSPECIFIED )
-    : std::runtime_error(message), type_(type) {}
-
-  //! Prints thrown error message to stderr.
-  virtual void printMessage( void ) const
-    { std::cerr << '\n' << what() << "\n\n"; }
-
-  //! Returns the thrown error message type.
-  virtual const Type& getType(void) const { return type_; }
-
-  //! Returns the thrown error message string.
-  virtual const std::string getMessage(void) const
-    { return std::string(what()); }
-
- protected:
-  Type type_;
+/* class RTAUDIO_DLL_PUBLIC RtAudioError : public std::runtime_error */
+/* { */
+/*  public: */
+/*   //! Defined RtAudioError types. */
+/*   enum Type { */
+/*     NO_ERROR,          /\*!< No error. *\/ */
+/*     WARNING,           /\*!< A non-critical error. *\/ */
+/*     UNSPECIFIED,       /\*!< The default, unspecified error type. *\/ */
+/*     NO_DEVICES_FOUND,  /\*!< No devices found on system. *\/ */
+/*     INVALID_DEVICE,    /\*!< An invalid device ID was specified. *\/ */
+/*     DEVICE_DISCONNECT, /\*!< A device in use was disconnected. *\/ */
+/*     MEMORY_ERROR,      /\*!< An error occured during memory allocation. *\/ */
+/*     INVALID_PARAMETER, /\*!< An invalid parameter was specified to a function. *\/ */
+/*     INVALID_USE,       /\*!< The function was called incorrectly. *\/ */
+/*     DRIVER_ERROR,      /\*!< A system driver error occured. *\/ */
+/*     SYSTEM_ERROR,      /\*!< A system error occured. *\/ */
+/*     THREAD_ERROR       /\*!< A thread error occured. *\/ */
+/*   }; */
+
+/*   //! The constructor. */
+/*   RtAudioError( const std::string& message, */
+/*                 Type type = RtAudioError::UNSPECIFIED ) */
+/*     : std::runtime_error(message), type_(type) {} */
+
+/*   //! Prints error message to stderr. */
+/*   virtual void printMessage( void ) const */
+/*     { std::cerr << '\n' << what() << "\n\n"; } */
+
+/*   //! Returns the error message type. */
+/*   virtual const Type& getType(void) const { return type_; } */
+
+/*   //! Returns the error message string. */
+/*   virtual const std::string getMessage(void) const */
+/*     { return std::string(what()); } */
+
+/*  protected: */
+/*   Type type_; */
+/* }; */
+
+enum RtAudioErrorType {
+  RTAUDIO_NO_ERROR,          /*!< No error. */
+  RTAUDIO_WARNING,           /*!< A non-critical error. */
+  RTAUDIO_UNKNOWN_ERROR,     /*!< An unspecified error type. */
+  RTAUDIO_NO_DEVICES_FOUND,  /*!< No devices found on system. */
+  RTAUDIO_INVALID_DEVICE,    /*!< An invalid device ID was specified. */
+  RTAUDIO_DEVICE_DISCONNECT, /*!< A device in use was disconnected. */
+  RTAUDIO_MEMORY_ERROR,      /*!< An error occured during memory allocation. */
+  RTAUDIO_INVALID_PARAMETER, /*!< An invalid parameter was specified to a function. */
+  RTAUDIO_INVALID_USE,       /*!< The function was called incorrectly. */
+  RTAUDIO_DRIVER_ERROR,      /*!< A system driver error occurred. */
+  RTAUDIO_SYSTEM_ERROR,      /*!< A system error occurred. */
+  RTAUDIO_THREAD_ERROR       /*!< A thread error occurred. */
 };
 
 //! RtAudio error callback function prototype.
@@ -260,7 +274,7 @@ class RTAUDIO_DLL_PUBLIC RtAudioError : public std::runtime_error
     \param type Type of error.
     \param errorText Error description.
  */
-typedef void (*RtAudioErrorCallback)( RtAudioError::Type type, const std::string &errorText );
+typedef void (*RtAudioErrorCallback)( RtAudioErrorType type, const std::string &errorText );
 
 // **************************************************************** //
 //
@@ -460,14 +474,16 @@ class RTAUDIO_DLL_PUBLIC RtAudio
 
   //! Return an RtAudio::DeviceInfo structure for a specified device number.
   /*!
-
     Any device integer between 0 and getDeviceCount() - 1 is valid.
-    If an invalid argument is provided, an RtAudioError (type = INVALID_USE)
-    will be thrown.  If a device is busy or otherwise unavailable, the
-    structure member "probed" will have a value of "false" and all
-    other members are undefined.  If the specified device is the
-    current default input or output device, the corresponding
-    "isDefault" member will have a value of "true".
+    If an invalid argument is provided, an RTAUDIO_INVALID_USE
+    will be passed to the user-provided errorCallback function (or
+    otherwise printed to stderr), the structure member "probed" will
+    have a value of "false" and all other members will be undefined.
+    If a device is busy or otherwise unavailable, the structure member
+    "probed" will have a value of "false" and all other members will
+    be undefined.  If the specified device is the current default
+    input or output device, the corresponding "isDefault" member will
+    have a value of "true".
   */
   RtAudio::DeviceInfo getDeviceInfo( unsigned int device );
 
@@ -493,10 +509,10 @@ class RTAUDIO_DLL_PUBLIC RtAudio
 
   //! A public function for opening a stream with the specified parameters.
   /*!
-    An RtAudioError (type = SYSTEM_ERROR) is thrown if a stream cannot be
+    An RTAUDIO_SYSTEM_ERROR is returned if a stream cannot be
     opened with the specified parameters or an error occurs during
-    processing.  An RtAudioError (type = INVALID_USE) is thrown if any
-    invalid device ID or channel number parameters are specified.
+    processing.  An RTAUDIO_INVALID_USE is returned if a stream
+    is already open or any invalid stream parameters are specified.
 
     \param outputParameters Specifies output stream parameters to use
            when opening a stream, including a device ID, number of channels,
@@ -528,49 +544,44 @@ class RTAUDIO_DLL_PUBLIC RtAudio
            chosen.  If the RTAUDIO_MINIMIZE_LATENCY flag bit is set, the
            lowest allowable value is used.  The actual value used is
            returned via the structure argument.  The parameter is API dependent.
-    \param errorCallback A client-defined function that will be invoked
-           when an error has occured.
   */
-  //void openStream( RtAudio::StreamParameters *outputParameters,
-  RtAudioError::Type openStream( RtAudio::StreamParameters *outputParameters,
+  RtAudioErrorType openStream( RtAudio::StreamParameters *outputParameters,
                                  RtAudio::StreamParameters *inputParameters,
                                  RtAudioFormat format, unsigned int sampleRate,
                                  unsigned int *bufferFrames, RtAudioCallback callback,
-                                 void *userData = NULL, RtAudio::StreamOptions *options = NULL ); //, RtAudioErrorCallback errorCallback = NULL );
+                                 void *userData = NULL, RtAudio::StreamOptions *options = NULL );
 
   //! A function that closes a stream and frees any associated stream memory.
   /*!
-    If a stream is not open, this function issues a warning and
-    returns (no exception is thrown).
+    If a stream is not open, an RTAUDIO_WARNING will be
+    passed to the user-provided errorCallback function (or otherwise
+    printed to stderr).
   */
   void closeStream( void );
 
   //! A function that starts a stream.
   /*!
-    An RtAudioError::SYSTEM_ERROR is returned if an error occurs
-    during processing. An RtAudioError:WARNING is returned if a
+    An RTAUDIO_SYSTEM_ERROR is returned if an error occurs
+    during processing. An RTAUDIO_WARNING is returned if a
     stream is not open or is already running.
   */
-  //void startStream( void );
-  RtAudioError::Type startStream( void );
+  RtAudioErrorType startStream( void );
 
   //! Stop a stream, allowing any samples remaining in the output queue to be played.
   /*!
-    An RtAudioError::SYSTEM_ERROR is returned if an error occurs
-    during processing.  An RtAudioError::WARNING is returned if a
+    An RTAUDIO_SYSTEM_ERROR is returned if an error occurs
+    during processing.  An RTAUDIO_WARNING is returned if a
     stream is not open or is already stopped.
   */
-  //void stopStream( void );
-  RtAudioError::Type stopStream( void );
+  RtAudioErrorType stopStream( void );
 
   //! Stop a stream, discarding any samples remaining in the input/output queue.
   /*!
-    An RtAudioError::SYSTEM_ERROR is returned if an error occurs
-    during processing.  An RtAudioError::WARNING is returned if a
+    An RTAUDIO_SYSTEM_ERROR is returned if an error occurs
+    during processing.  An RTAUDIO_WARNING is returned if a
     stream is not open or is already stopped.
   */
-  //void abortStream( void );
-  RtAudioError::Type abortStream( void );
+  RtAudioErrorType abortStream( void );
 
   //! Returns true if a stream is open and false if not.
   bool isStreamOpen( void ) const;
@@ -580,14 +591,11 @@ class RTAUDIO_DLL_PUBLIC RtAudio
 
   //! Returns the number of elapsed seconds since the stream was started.
   /*!
-    If a stream is not open, an RtAudioError (type = INVALID_USE) will be thrown.
+    If a stream is not open, the returned value may not be valid.
   */
   double getStreamTime( void );
 
   //! Set the stream time to a time in seconds greater than or equal to 0.0.
-  /*!
-    If a stream is not open, an RtAudioError (type = INVALID_USE) will be thrown.
-  */
   void setStreamTime( double time );
 
   //! Returns the internal stream latency in sample frames.
@@ -595,9 +603,9 @@ class RTAUDIO_DLL_PUBLIC RtAudio
     The stream latency refers to delay in audio input and/or output
     caused by internal buffering by the audio system and/or hardware.
     For duplex streams, the returned value will represent the sum of
-    the input and output latencies.  If a stream is not open, an
-    RtAudioError (type = INVALID_USE) will be thrown.  If the API does not
-    report latency, the return value will be zero.
+    the input and output latencies.  If a stream is not open, the
+    returned value will be invalid.  If the API does not report
+    latency, the return value will be zero.
   */
   long getStreamLatency( void );
 
@@ -662,7 +670,6 @@ struct CallbackInfo {
   ThreadHandle thread;
   void *callback;
   void *userData;
-  //  void *errorCallback;
   void *apiInfo;   // void pointer for API specific callback information
   bool isRunning;
   bool doRealtime;
@@ -671,7 +678,7 @@ struct CallbackInfo {
 
   // Default constructor.
   CallbackInfo()
-  :object(0), callback(0), userData(0), apiInfo(0), isRunning(false), doRealtime(false), priority(0), deviceDisconnected(false) {} // errorCallback(0), 
+  :object(0), callback(0), userData(0), apiInfo(0), isRunning(false), doRealtime(false), priority(0), deviceDisconnected(false) {}
 };
 
 // **************************************************************** //
@@ -734,21 +741,17 @@ public:
   virtual RtAudio::DeviceInfo getDeviceInfo( unsigned int device ) = 0;
   virtual unsigned int getDefaultInputDevice( void );
   virtual unsigned int getDefaultOutputDevice( void );
-  //void openStream( RtAudio::StreamParameters *outputParameters,
-  RtAudioError::Type openStream( RtAudio::StreamParameters *outputParameters,
+  RtAudioErrorType openStream( RtAudio::StreamParameters *outputParameters,
                                  RtAudio::StreamParameters *inputParameters,
                                  RtAudioFormat format, unsigned int sampleRate,
                                  unsigned int *bufferFrames, RtAudioCallback callback,
-                                 void *userData, RtAudio::StreamOptions *options ); //, RtAudioErrorCallback errorCallback );
+                                 void *userData, RtAudio::StreamOptions *options );
   virtual void closeStream( void );
-  //virtual void startStream( void ) = 0;
-  virtual RtAudioError::Type startStream( void ) = 0;
-  //virtual void stopStream( void ) = 0;
-  //virtual void abortStream( void ) = 0;
-  virtual RtAudioError::Type stopStream( void ) = 0;
-  virtual RtAudioError::Type abortStream( void ) = 0;
+  virtual RtAudioErrorType startStream( void ) = 0;
+  virtual RtAudioErrorType stopStream( void ) = 0;
+  virtual RtAudioErrorType abortStream( void ) = 0;
   long getStreamLatency( void );
-  unsigned int getStreamSampleRate( void ); // const { return stream_.sampleRate; }
+  unsigned int getStreamSampleRate( void );
   virtual double getStreamTime( void ) const { return stream_.streamTime; }
   virtual void setStreamTime( double time );
   bool isStreamOpen( void ) const { return stream_.state != STREAM_CLOSED; }
@@ -832,7 +835,6 @@ protected:
   RtAudioErrorCallback errorCallback_;
   bool showWarnings_;
   RtApiStream stream_;
-  //bool firstErrorOccurred_;
 
   /*!
     Protected, api-specific method that attempts to open a device
@@ -856,11 +858,10 @@ protected:
     Protected common method that throws an RtAudioError (type =
     INVALID_USE) if a stream is not open.
   */
-  void verifyStream( void );
+  //void verifyStream( void );
 
   //! Protected common error method to allow global control over error handling.
-  //void error( RtAudioError::Type type );
-  RtAudioError::Type error( RtAudioError::Type type );
+  RtAudioErrorType error( RtAudioErrorType type );
 
   /*!
     Protected method used to perform format, channel number, and/or interleaving
@@ -891,11 +892,11 @@ inline unsigned int RtAudio :: getDefaultInputDevice( void ) { return rtapi_->ge
 inline unsigned int RtAudio :: getDefaultOutputDevice( void ) { return rtapi_->getDefaultOutputDevice(); }
 inline void RtAudio :: closeStream( void ) { return rtapi_->closeStream(); }
 //inline void RtAudio :: startStream( void ) { return rtapi_->startStream(); }
-inline RtAudioError::Type RtAudio :: startStream( void ) { return rtapi_->startStream(); }
+inline RtAudioErrorType RtAudio :: startStream( void ) { return rtapi_->startStream(); }
 //inline void RtAudio :: stopStream( void )  { return rtapi_->stopStream(); }
 //inline void RtAudio :: abortStream( void ) { return rtapi_->abortStream(); }
-inline RtAudioError::Type RtAudio :: stopStream( void )  { return rtapi_->stopStream(); }
-inline RtAudioError::Type RtAudio :: abortStream( void ) { return rtapi_->abortStream(); }
+inline RtAudioErrorType RtAudio :: stopStream( void )  { return rtapi_->stopStream(); }
+inline RtAudioErrorType RtAudio :: abortStream( void ) { return rtapi_->abortStream(); }
 inline bool RtAudio :: isStreamOpen( void ) const { return rtapi_->isStreamOpen(); }
 inline bool RtAudio :: isStreamRunning( void ) const { return rtapi_->isStreamRunning(); }
 inline long RtAudio :: getStreamLatency( void ) { return rtapi_->getStreamLatency(); }
@@ -923,12 +924,9 @@ public:
   unsigned int getDefaultOutputDevice( void );
   unsigned int getDefaultInputDevice( void );
   void closeStream( void );
-  //void startStream( void );
-  RtAudioError::Type startStream( void );
-  //void stopStream( void ;)
-  RtAudioError::Type stopStream( void );
-  //void abortStream( void );
-  RtAudioError::Type abortStream( void );
+  RtAudioErrorType startStream( void );
+  RtAudioErrorType stopStream( void );
+  RtAudioErrorType abortStream( void );
 
   // This function is intended for internal use only.  It must be
   // public because it is called by the internal callback handler,
@@ -1197,14 +1195,14 @@ class RtApiDummy: public RtApi
 {
 public:
 
-  RtApiDummy() { errorText_ = "RtApiDummy: This class provides no functionality."; error( RtAudioError::WARNING ); }
+  RtApiDummy() { errorText_ = "RtApiDummy: This class provides no functionality."; error( RTAUDIO_WARNING ); }
   RtAudio::Api getCurrentApi( void ) { return RtAudio::RTAUDIO_DUMMY; }
   unsigned int getDeviceCount( void ) { return 0; }
   RtAudio::DeviceInfo getDeviceInfo( unsigned int /*device*/ ) { RtAudio::DeviceInfo info; return info; }
   void closeStream( void ) {}
-  void startStream( void ) {}
-  void stopStream( void ) {}
-  void abortStream( void ) {}
+  RtAudioErrorType startStream( void ) { return RTAUDIO_NO_ERROR; }
+  RtAudioErrorType stopStream( void ) { return RTAUDIO_NO_ERROR; }
+  RtAudioErrorType abortStream( void ) { return RTAUDIO_NO_ERROR; }
 
   private:
 
diff --git a/configure.ac b/configure.ac
index 43c054a..f667fe1 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1,5 +1,5 @@
 # Process this file with autoconf to produce a configure script.
-AC_INIT(RtAudio, 5.1.0, gary@music.mcgill.ca, rtaudio)
+AC_INIT(RtAudio, 6.0.0beta1, gary@music.mcgill.ca, rtaudio)
 AC_CONFIG_AUX_DIR(config)
 AC_CONFIG_SRCDIR(RtAudio.cpp)
 AC_CONFIG_FILES([rtaudio.pc Makefile tests/Makefile doc/Makefile doc/doxygen/Doxyfile])
diff --git a/tests/playsaw.cpp b/tests/playsaw.cpp
index e875313..56e693f 100644
--- a/tests/playsaw.cpp
+++ b/tests/playsaw.cpp
@@ -64,7 +64,7 @@ void usage( void ) {
   exit( 0 );
 }
 
-void errorCallback( RtAudioError::Type /*type*/, const std::string &errorText )
+void errorCallback( RtAudioErrorType /*type*/, const std::string &errorText )
 {
   // This example error handling function simply outputs the error message to stderr.
   std::cerr << "\nerrorCallback: " << errorText << "\n\n";