Ordinarily, I'd be embarrassed to admit how many electronic devices I have sharing a single circuit. However, since it may help you, my 7500 is absolutely quiet and it's sharing a single 15A circuit with a LOT of equipment in two rooms.

I'd have an electrician look at the circuit or do some DIY testing if you're confident you won't kill yourself. Determine if you have a good ground. Check the polarity of the outlet. Check for high enough (or too high) voltage. Some equipment is more sensitive to voltage irregularities, miswire conditions, etc.

A simple voltage meter may tell you a lot.

- Jason