Here's another question for you, Marcel, in the SLOCLONE schematics I'm working with, the Clean/OD channel-switching is done using opto-isolators that consist of a Led and an LDR, or Light dependent Resistor, a mate of mine who used to do amp servicing told me that those Led/LDR opto-isolators tend not to be very reliable when used in channel-switching amps because they "get the daylights flogged out of them", so, I was thinking of using some 5V relays to do the channel-switching instead of using Led/LDR opto-isolators, that should be quite doable, shouldn't it? I think my Marshall MA100C amp uses relays for it's channel-switching, I'll just need to come-up with a relatively simple to build relay driver circuit that can run on 5V.