Hi there!
I’m newby in “Zynthian” but…
My zynthian project is almost done…
I used the “prototype-1” scheme with a PI4 (source: A Build with Variations), a screen, four encoders and an USB Audio… It’s my “speciality” becouse, I just I sacrificed my old ALESIS io2 Express USB sound card, and my EDIROL PCR-800 MIDI master keyboard…
I dissasambled the io2, and built in into the PRC-800 with the zynthian…
The result a bit ugly yet now 
but it’s will be nicer of course.
The most important thing is my zynthian setup is alive! 
Raspberry PI4B / 4G RAM
Waveshare 4.3 inch DSI LCD
PROTOTYPE-1 wiring
ALESIS io2 sound card with
- USB MIDI IN/OUT
- DIN MIDI IN/OUT
- 2x balanced AUDIO IN MIC/LINE/GUITAR with +48V phantom
- 2x AUDIO insert IN (for external FX)
- 2x AUDIO OUT (44100 Hz/24bit with 5ms latency)
- 1x Phones OUT
EDIROL PCR-800 MIDI keyboard/house
