Hi Xavier!
Thanks for this great project, and glad to see it is improving also, now with preenfm3! :-)
Is it possible to have a per-channel Mixer setting also for the preenfm2, where the volume/pan settings can be made globally for the selected Channel, and not per Operator? As for the pan setting, it could hard-pan the Channel making it easier to make a Left-Right Audio Out split to two mono channels. And it should stay globally, so the newly loaded sounds don't change it.
As there are 4 knobs, there could be a place also for some other Performance settings, maybe the MIDI channel, and also for some select CC-number (just quick ideas, maybe there could be some even more meaningful settings)
Bests,
Gas