The problem I had with all the regular circuits was too much gain (and thus too much hum/noise gain), and not enough drive (without a cathode follower). I fixed this by using a simple, linear circuit with a small power tube. This baby has a gain of ~4.5, Zout of 200Ω, bandwidth (+0, -1dB) of 8Hz to 300KHz (!), and hum+noise low enough to be difficult to measure with a lab millivoltmeter, about 0.1mV.

The number-of-inputs problem is solvable with any circuit. I do this too, because I can source a nice silver-contact toggle switch for about six bucks, where an equivalent quality rotary is about forty with a nice knob.

I'm going to put this project up on my site in the next couple of days, but if you want to look at it right now, The Owner's manual is up at:

http://www.AudioTropic.net/AudioTropicMobiusUsersManual/UsersManual.html

All the technical details are in there.

Aloha,

Poinz