Belkin PF60 from ecost.com. Panamax has some very highly rated ones as well.
Same here.
+1.
eCost, PF60, a couple of years ago. I snagged it on sale for like $150 or so.
As far as I can tell, it makes no difference in sound quality. But it does eliminate the occasional and nearly inaudible 'tick' or 'snap' that I'd get through my speakers whenever the clothes dryer, room AC, or neighbor's HVAC system (we share a transformer on the pole) kicked on and my system was on but not playing audio. So it does actually "clean" the power for me, better than my old 'surge protector' did. Note the quotes around clean. All I know is that it is a benefit in my system in my current home.
Also importantly, I like it for cable organization. It just looks a bit neater behind the AV Rack with it than without it. And it just generally looks cool. Who doesn't love a heavy metallic box with blue lights & an ever-changing LCD display in their AV Rack?
It is interesting to see how many amps my system is pulling when I do different things. And also interesting to see how much my home voltage varies from minute to minute. Power in my town is notoriously variable, plus I live in an old house (set up for GAS lighting), in a neighborhood of old homes. So yeah, I feel like I need to have some sort of 21st century barrier between my electronics and my wall.