I've used a number of power conditioners, and found after extensive listening that they sometimes (but not always) help the system. Most work best if you plug it into the circuit and plug NOTHING into the unit itself. Plugging ANYTHING into the unit generally ruins the sound..collapses the sound stage, adds grain and grit, does funny things with the phasing, etc. I'm using Richard Gray stuff on my big system and it helps slightly, but again, I have nothing plugged into it. I'm using API on my video system, and it helps a little there too, but again only if nothing is plugged into it.