I’ve been searching for a good minimal mixer for awhile, and have considered building something custom a few different times but haven’t gotten around to it.
The Lifeforms System Interface definitely seems to be the closest to what I imagine as an ideal minimal mixer. Big fan of the toggle main/bus switches (could imagine using them to send bursts of audio to the bus output with a delay feeding back into the mixer or something like that) though for my own uses I’d probably want to set it up in its own case for times when I wouldn’t have the modular, which makes it a more costly option.
The Vixen is also a very interesting option, and could power some pedals or other 9V synths up to its 3A max. I mainly just wish the primary knobs (channel volumes and master volume) were not tiny, and I personally think the full size 1/4" send I/O is odd given that one can easily use 3.5mm<>1/4" adapter cables and that could have made the panel much less crowded. I get the idea of avoiding adapters, but it means you have pretty huge cables hanging off a relatively tiny device.
Is anyone using a KOMA Field Kit as their main performance mixer? Not really minimal in a pure sense, but if you see value in the rest of what it does, the mixer is simple and seems effective…but it isn’t stereo 
