Munching this results in a 923-byte file.
THIS IS THE BEST 1K EVER
EDIT: Resaving the base song in Schism results in a 1067-byte file. The base song was tracked in ImpulseTracker, as you can tell by the stupid amount of MIDI and/or timestamp info.
EDIT: Apparently it wasn't tracked in IT. It's probably MIDI info. Thanks Modplug.