Hi John - I did indeed try a beefy TrippLite computer UPS on the battery jack which provides constant filtered power and had the same problem. My Monster Power strip is the HTS850. It does indeed have clean power as a feature, "Stage 1 Clean Power." I guess since the AVR520 has been going into standby while connected even to a UPS we're dealing with something else here.

As far as testing other speakers goes, the only ones I have now would likely be blown if I crank the AVR520 up to the point where it cuts out. Marc has sold this particular setup though and apparently he hasn't seen this unit have any trouble with the M80Ti's.

Is there anything else you (or any other forum members) suggest I might try or should I assume I have a bad receiver?

Thanks,

Doug