Thanks again, Kevin, taken from your suggestion the most convenient way of resetting the CoreAudio server preferences without rebooting seems to be: # clear CoreAudio preferences sudo truncate -s 0 /Library/Preferences/Audio/com.apple.audio.* # change owner to prevent rewrite sudo chown root /Library/Preferences/Audio/com.apple.audio.* sudo killall coreaudiod # reset owner to allow rewrite sudo chown _coreaudiod /Library/Preferences/Audio/com.apple.audio.* sudo killall coreaudiod Thanks

Though this seems to generally work, the system (CoreMIDI?) can come into a situation where logging just stops.