On OS X on the MacBook, which has two input sources (mic and line in) and one output source. $ jackd -d coreaudio jackd 0.102.20 Copyright 2001-2005 Paul Davis and others. jackd comes with ABSOLUTELY NO WARRANTY This is free software, and you are welcome to redistribute it under certain conditions; see the file COPYING for details JACK compiled with POSIX SHM support. loading driver .. Default input and output devices are not the same !! Cannot open default device Cannot open the coreaudio driver cannot load driver module coreaudio no message buffer overruns 'jackd -d coreaudio -C' works fine, as does 'jackd -d coreaudio -P'. Fine as in it does what you expect, which is give you either capture or playback, but not both. The -l output is (snipped): Device name = 'Built-in Microphone', internal_name = 'AppleHDAEngineInput:1' (to be used as -d parameter) Device name = 'Built-in Input', internal_name = 'AppleHDAEngineInput:2' (to be used as -d parameter) Device name = 'Built-in Output', internal_name = 'AppleHDAEngineOutput:0' (to be used as -d parameter) I can select which capture device to use using the -d parameter. So if I do "jackd -d coreaudio -D -d 'AppleHDAEngineInput:1'" that doesn't crash, but gives me only capture and no playback. I've tried a few other variations on the theme, including things like "jackd -d coreaudio -C -d 'AppleHDAEngineInput:1' -P -d 'AppleHDAEngineOutput:0'" but to no avail. Am I missing something obvious? Has anyone else had this trouble? Thanks! -- Hans Fugal ; http://hans.fugal.net There's nothing remarkable about it. All one has to do is hit the right keys at the right time and the instrument plays itself. -- Johann Sebastian Bach