Here’s what Rheyne has to say about the technical details:
A demonstration of how “Channel Rotation” on a KMI QuNexus can be used to turn multiple mono synths into one polyphonic synth.
With nothing connected to the VC MIX inputs on the Mothers, the VC MIX output and some multiples are controlling all three filters with one knob.
The MIDI DIN outputs of an iConnectMIDI4+ are triggering the synths on three MIDI channels.
MIDI and audio loops are recorded with Ableton Live. Reverb is also from Ableton.
You can download the 24bit/48khz WAV via the SoundCloud embed below: