I've installed cmus (http://cmus.sourceforge.net/) both via the source code and dependencies, compiled myself, and via Homebrew (https://github.com/mxcl/homebrew) standard install (it installs all the dependencies as well). Both versions have had the same problem: whenever anything is plugged into the output jack (say, as I'm switching from headphones to speakers), the music stops. cmus is still playing, but no sound comes out until I "set output_plugin:ao" manually again. Annoying. Anyone know why this is?
According to the cmus man page,
To append the option:
This is an old one, but it helped solve my problem.
In my case I have soundflower installed. I incidentally got some sound in my headphones by a combination of plug/unplug, however the sound level was not adjustable, it ignored the system sound settings, except it muted when the system sound was set to mute.
To fix the issue:
Now I can plug/unplug headphones, restart cmus, sound output properly delivered. Hope that helps