I've seen that if i compile Vavoom without Vorbis support (--without-vorbis) and the external music files (vmusic-1.0.zip package) are installed, if "External music" menu item is enabled no music is played at all. It could be nice if, in this case, music support fallback to MIDI.

Also, I noticed that the music "jumps" while maps are being loaded and it doesn't stops when you pause the game.