High quality Speaker switch box for multiple amps?


Stupid idea, I know. But if I wanted to have 2 or 3 separate amps (NOT running at same time, of course) to choose from with 1 preamp. Is there a switch box (preamp to box, box to multiple amps with a,b, c switch, box to main speakers) that is of high quality and will have very minimal effect on sound? Of course I would keep same brand/model of speaker cable at all points. Just curious
aberyclark
Van alstine has a box that can switch all inputs and outputs and level match them. About $1500.00. 

To make those Amplifier switcher safer for all Amplifiers, parallel all speaker outputs with 25 -100 ohm  5watts resistor.
if testing, you could also try running one amp into each speaker and using the pre-amp to "switch"

this won't test the sound staging and some other things, but costs nothing