Please explain why this would not work? If you keep the jumper and connect both amps the speaker will sense the signal from either top or bottom binding post. If OP turns off his SS amp, his speaker will only get signal from the amp that is active.
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I saw a person do this with class D amps. He had the class Ds turned OFF and the the tube gear playing. I heard a high pitched sound and it blew a 20 amp house breaker. The caps in the SS gear charged and BLEW the transformer on the tube gear. Guess whos gear it was?.. MINE...
You have to do what the two gent mentioned above. Dummy loads, I use a 3 position switch. Center is hooked to nothing. I don't trust switches either.. A space between contacts is even better.. 3 position vs 2
Chicken feedin' time
Regards