I'm not sure if this has been talked about before, i've done a bit of looking around and found nothing on it.
I think it would be great to have an option where in jukebox mode instead of playing the song through the audio device, it just sends the filepath of the song to play to xbmc which then handles playing it.
My entire setup is based around XBMC as a frontend, and i'm setting up a tablet device designated just for Subsonic jukebox music selection however how it is currently it will play 'behind' whatevers playing and not have any visualisation and such.
It would be relatively simple to implement (just visiting a url when a file is supposed to be played?) but i think it would make great integration and basically give subsonic a nice frontend player for those that have it on a non-pc setup.