I've been pondering how I might do this of late. I've got an amp I particularly like with an excellent loop and I'd love to rig up a preamp so I can have a 'clean' channel. Does anyone know how this could be done? I've read that the new MTS preamps will add a 'channel' to single ch amps etc but am not sure how it could be easily accomplished without ground loops and hums etc and have things switch reasonably easily. I have a little BOSS GT-1 which would work great for clean tones.