Karmapolice,
Sorry that I'm not familiar with all your audio equipment.
Are both amps plugged into the same wall outlet, and/or outlet strip? If so, it's beyond my 40 years of electronics how malfunctioning strip protection circuits could single out any "matching" components plugged into it.
Anyway, you could also try running both amps into the same wall outlet directly, and the remaining components from another outlet (via extension cord) for testing purposes. My feeling is that your problem will return, but please continue with any recommended diagnosis.