I pushed a simple implementation of the idea to the "actions" branch on the git repo. It is a few functions added to emms.el. Please check it out.
It operates on the track at point. So once you are over a playlist track you can eval something like: (emms-actions-add #'(lambda (track) (ignore track) (emms-volume-raise)) 'before-action) ...and then also: (emms-actions-add #'(lambda (track) (ignore track) (emms-volume-lower)) 'after-action) Then, when you play the track as part of the playlist, the volume should be raised before the tracks starts, and lowered after it completes. Tell me what you think. -- "Cut your own wood and it will warm you twice"