I use a Furman IT-20 Series II Balanced Power Conditioner. This puts out a +/- line voltage centered at ground, instead of the usual +120vac clamped to neutral/ground.
It also has a lot of filters, isolated digital and analog supply and a toroidal transformer. Not cheap, but I got a factory refurbished one for 1/2 price.
This feeds the system I'm building: Marantz SR8002 Rcvr, Sierra1 mains/center, Rhythmik F-15 sub (on order, to replace Infinity PS-10); surrounds will be Sierra1, to replace Klipsch RSX-3 =) ; Sony lcd/bluray, Pioneer PD-F1009 300 CD jukebox, Dishnet hdtv rcvr, plus misc. analog/digital a/v production gear.