I was in a similar position a few years ago -- wanted a switcher to change between a tube and a solid state amp. One of my preferred dealers, who's opinion I give weight to, said that there was no way to do it without degrading the sonics. I never took steps to confirm that and just stuck to switching out speaker cables when I switch between amps. However, both amps are hooked up to the same preamp, so no cable switching there.
