www.megadrum.info

Should be possible to bypass USB hardware entirely whilst providing for longer cable lengths by
using SPDIF - after the positional sensing is done of course

For an overview try: http://www.epanorama.net/documents/audio/spdif.html

You can use the MIDI interface for longer cables.

SPDIF is only digital audio, not MIDI data

Looks to me like the spec' will allow this transport stream for anything.
...plenty of spare clock cycles going to waste there on the PIC