I have very high confidence in my A/C power feed. I have a 200 amp service, with 14ga copper feeding the circuit which feeds only my amp, laptop and Squeezebox. With the exception of my clothes drier, I have no motor or inductive loads on my panel (and the behavior I experience is unrelated to my clothes drier).
The only time I have experienced nuisance trips with my production board 'II was when my power was waaaay out of spec - the HV supply was designed to prevent most all of these trips. Do you have anything else on the power circuit with the amp that might be producing surges or noise on the line?
So I'm looking for other ideas. What can I measure or observe to try to narrow down the cause of my problem. Back in May, I worked back through the startup proceedure/checklist for the SOHA and everything measured was within the suggested ranges. I really like the way my SOHA sounds, but having it drop out for anywhere from .5 to 2 seconds while I'm listening to it is saddening.