That's a pretty awesome piece of old tech. Man that brings back memories.

I wonder what happens if you have like 20 midi tracks. Do the buttons only control the first several tracks or does it group them?

I don't have any of my old MIDI files, but I do have my entire collection of mod/s3m/other various tracker files .. many of them original works that probably aren't available anywhere. This makes me think I should really post them up at some point.