I've always used Renoise, before I even got the XW-P1. It's a tracker very reminiscent of ProTracker for the Amiga. Nice touch is it seems to play ball with the "Play" button on the XW-P1, so sequencing the Step sequencer along with Renoise works a charm You can use Software VSTs (obviously), send MIDI Data out, input data via MIDI, use as many/few tracks as you like, adjust velocity using Hex data at each note and route audio through specific tracks. http://www.renoise.com/