I've been using mocp for a while now (running under Fedora 23) and I find it to be a nice music player.
When I adjust the volume in mocp it affect the system volume, for example if I would turn down the volume to 0% in mocp, all other audio is also affected and entirely silent.
Is it possible to have a "application-only" volume control in mocp? This would be similar to for example VLC, audacious et.c and how those applications function. If I turn down the volume to 50% in VLC, it is only VLC that is affected.