I was originally thinking of keeping this one-synth challenge restrained to a single pass - meaning, no multi-tracking, but only as much as one could achieve with a single take. Now THAT would be the most fascinating challenge of all, and would highlight the chosen synthesizer in an exceptional way. But I suppose most folks would think that's too stringent and would insist on multi-tracking galore. I won't make an issue out of this, but a single track would make demands on the synthesist and their instrument that multi-tracking would not, and would allow for a crisp clean presentation of the instrument's character and capabilities, un-muddled by layers. It's that "wall of sound" density that spoils the original intent.
Perhaps there should be a double challenge - a single track thread and a multi track.
I can think of two complications from my situation. First, I chain keyboard and module/rack versions for a larger sound. But because these concern the identical instrument in two forms, I think it should be allowed. It may be a system, but it's still the one same instrument. And second: bass pedals. I always use them. Even though they concern the same instrument - the Prophet '08 - I think they should not be allowed. The standard should be that the music must be triggered from a single keyboard and panel.