I auditioned a RGPC in the home for a week. At first I was satisfied with the seemingly lower noise floor/"blacker" background. But.... eventually I noticed the RGPC tended to reduce dynamics. For this reason I returned the unit to the chagrin of the would-be retailer.
Which RGPC model did you use? Also, what's the total current draw of your amplifier(wpc)?
I have a pretty annoying 60/120Hz hum in my AC supply. he hum was never noticeable when I had my solid state amp and 90dB speakers. But, when I swithced to my 97dB system with low power SET amps, it was really annoying. The hum was slightly audible from my listening position 12+ feet away when no music was on. Just knowing it was there after all I'd spent on my system, drove me nuts. I tried regrounding my circuit breaker line to my copper water line, but no luck. I checked and regrounded every outlet in my living room, also.
A good friend(and audio dealer) loaned me the RGPC Pole Pig and a 400 unit to try out. I plugged the Pole Pig into the wall and the 400 unit into the Pole Pig. Amps got plugged into the 400 unit and sources the Pole Pig. Luckily, my low power SET amps draw less ~120 watts at idle according to both manufacturers. (class A/SET amps draw same power at idle as full power)
I got an immediate huge difference in my system performance. You'll never know how much noise is in your AC line until it is gone. Now I understand the saying "black background" because that's exactly what I got. Notes, tones, individual instruments were so much more clearly defined - it was amazing. Decay and shimmer of cymbals was truly spectacular. I had no idea of my system's ultimate resolution until the RGPC system was inserted. As Steven Tyler sang "You ain't seen nothin' til your down on the muffin and shore to changin' your way".
Having said all that, I couldn't justify the cost of the RGPC system and ended up buying 6 surplus industrial Topaz 2.4kVA Ultra-Isolator transformers for less than 1/3 the price and wired them all in fully balanced configuration(halves the rating) providing 120dB common mode noise rejection apiece. I use one for each monoblock and one for my sources. Each source outlet has it's own filter to prevent noise crosstalk. I keep the other trannis in reserve in case I make the move back to high power amps.
And now, I've got the same "black background" for a few hundred bucks instead of $2,000. They may not look as good as the RGPC units, but in my system they work just as well.
