Here's a simple demo of my BTP2 music routine. The routine can produce a full chromatic scale over a five octave range, though the top and bottom octaves don't sound too wonderful (I doubt that the DPC would sound great on the really high or really low notes either).
Each of the four voices can independently play loudly or softly (though in this demo the volumes all tie together). This demo doesn't maintain vsync, though doing so probably wouldn't be too hard. The music player requires 46 cycles per scan line, leaving 30. Not enough to do a wonderful kernel, but enough to do something.