110V or 120V for Power Conditioner?

You won't hurt anything by trying both, and listening to each for awhile. You might find your system somewhat more dynamic with the 120V setting.

The H-10 owners manual I looked at on the APC website is really vague(as most manuals are)pertaining to you question.The AVR feature looks to be more than a 110v or 120v setting.I do know one thing for sure,this statement from the owners manual is B.S. "It is not necessary to turn this device or the devices connected to this device, off during a lighting storm" Folks,there is no device that will save your equipment from a direct lightning strike.I don't care how much it costs or what claims the company makes.If you value your equipment,UNPLUG it during lightning storms.I would be leery of buying from a company that makes an outrageous claim like this,but that's just me.

My current fluctuates from 118v-122v in CT. It is a simple task to check voltage at your outlets with a multi-meter.