I hear you, George, but it happens with two amps. I guess the way to be certain is to repeat the failure mode, turn off both amps and immediately measure the resistance across both speaker's terminals and compare. If one is way higher than the other then it's the resistor. If both are the same it's something else. (The only other thing to check is to swap cables at the speaker terminals instead of the amps to rule out a flaky cable connection).
Help with Sonus Faber Extrema issue
I have a pair of Sonus Faber Extremas hooked up to a pair of Parasound JC1 monoblocks. One of the speakers periodically will exhibit signicantly lower volume (down to almost no volume) in the middle of a listening session. It seems to occur when during more dynamic passages and also when the amps have been on for a while. If I turn everything off for a few minutes, the problem usually goes away. I reversed the speaker cables at the speakers and the same speaker still exhibited the issue, so the issue is with the speaker. What could cause this problem? Could it be a bad connection somewhere in the speaker? Could it be that crossover parts need to be changed due to age?