![Image](http://benryves.com/bin/gui.gif)
Download the preliminary release here: http://benryves.com/bin/qplayer_prelim.zip
(Note that the TI-83 version is probably horribly buggy - I haven't tried it (I don't own a TI-83), but it uses the same code as the 83+ so might work fine).
It comes with three songs I knocked out so you can try it out. If you don't have an adapter, I have recorded my TI and zipped up some MP3 files:
http://members.gamedev.net/benryves/quadplayer_mp3.zip
The song format is more logical than CalcMod or similar - you break up a song into sections (intro, end, verse, chorus etc) and then specify the order in which to play them, which means you could write a compressor to crunch down the size of the files. It's beyond me how you'd write such a tool, though.
Enjoy!