Bruce sold me an SS4 he had lying around the shop a few years ago. I use it as part of a big rack mount rig that runs 4 pres (3 M4s and a Mako Mak4) into 4 tube power amp channels. Switches silently between each dedicated pre/power amp channel and then has a single line out w/ individual level controls for the wet side of the rig. The main use of it is to run multiple heads or pre-amp/power amp channels into one set of speakers. The other benefit is the wet line out is after power amp, not between pre-amp and power amp. And switching is all Midi controllable. Mine is absolutely silent but I do run it with a decimator.