Right, I'm off the OT a bit. I'm thinking of things I would want in a pre. Like variable signal path (warm/transparent), easily powered, XLR/TRS inputs, and 4ch would the over the top. Not exactly small, which I think is becoming less of an issue. It's either tiny or it's not, in the sense of taper usage.
Great idea to take suggestions BEFORE building something. More should do the same.