In reply to:
In fact, I have read (but certainly not tested) that some UPS systems may actually degrade performance because of voltage fluctuations.
Yeah, thinking of it... The majority of reasonably priced online UPS's actually generate a "simulated" sine wave. This means that the UPS output is much "noisier" (full of high-order harmonics) than typical residential AC mains. This would be a non-issue for computers and most other digital gears. However, it could adversely affect the sound quality, depending on how good your amp's analog circuits are in rejecting the high-frequency noise contaminating the AC power line.
