Hi Gary Just wanted to let you know that I have been getting compilation warnings for RtAudio 4.0.4 when compiling on Mac 10.5.1. Besides that, everything works great. RtAudio.cpp:1175: warning: ‘AudioDeviceAddIOProc’ is deprecated (declared at /System/Library/Frameworks/CoreAudio.framework/Headers/ AudioHardware.h:2067) Best David