My input needs:
- Stereo Keys 1 (Nord Stage 3)
- Stereo Keys 2 (Nord Wave 2)
- Mono Backing Track (from iPad left)
- Mono Click Track (from iPad Right)
- Stereo Aux mix from Main Desk with my own mix from rest of the band
Output:
- Stereo output to Main desk (Containing mix of keys + Backing track)
- mono Click to Main desk (contraining click only)
- Headphone (Mix of keys, aux-mix, click track)
I found this cheap mixer from Aliexpress:

With two of those I could make everything as i want it and put everything in a case with exact the wiring I want inside. Painted it Nord-red.
Nice Corona project....
Works great!
I've added an extra input.
The top 4 knobs control the main output mix:
- External input
- Backing track volume
- keys1 volume
- keys 2 volume
The bottom 4 knobs control the headphone mix:
- Main output mix (Keys)
- Mix from Aux
- Click track level



