Could I use the PBC/6X with guitar preamps in the loops? I'd like to be able to switch preamps on the fly and direct the output of any preamp to either of one or two power amps. Each output would be connected to a separate tube power amp. I have a Mesa 20/20, and a few amps with serial effects loops. I will use the serial loops to break out after the preamp (send jack) and use a return jack as an input to just the power amp section. I am hoping to mix and match preamps with at least two different power amps. Do I need to use an isolation transformer on one of the outputs? Would my Ebtech Hum Eliminator do the trick? If so, is there any potential benefit or detriment from putting both the preamp outputs and power amp inputs through the Ebtech? What about pedals? I have never noticed any sound degradation when I've used it before.