Periodically (more often lately), I get low buzz/hum out of my speakers with no signal present. I believe it's coming from my H/K AV6-65 receiver. It doesn't appear to be tied to volume, other components (I disconnected them one by one), or other electrical appliances in the house. My home was built a little over a year old in a new development. This is driving me crazy and I purchased a Monster HTS5100 hoping the clean up the AC power going to the receiver. A day after hooking it all up, the hum is back. Grrr. The benefit of the HTS5100 is that there's a digital readout for voltage and amps and the unit will shut down when voltage is < 90 or > 132. With this constant readout, I'm making some progress in finding a cause. When things are good, the voltage moves around between 111 - 118, usually sitting at 114, and there's no audible impact. I've only ever seen the voltage reach 120 once, around 2 am late one night. The buzz/hum shows up when the voltage drops to 105 and below. The lowest I've seen the voltage is 103. The system draws 0.9 amps with everything off and idling and 3.8 - 4.0 with everything powered up at normal listening levels. I've started to track it and the low voltage times occur in the late afternoon until late evening (5 PM - 10 PM). I've been doing a bit of research and have found lots of conflicting information. I've read everything from "the power company should be delivering 123 volts +/- 6%" to "some areas having frequent brownouts where household voltage regularly drops to 95 volts". My home is at the end of a long road at the back of the subdivision and, my feeling is, during the hotter summer days the power delivery system in the development just isn't up to par. I am trying to determine what, if any, options I have. Are these voltage ratings "normal"? Should I be calling the power company, the home builder/developer, or resolving myself to the fact that I'll need a balanced power unit?