That sounds a little like putting up a barrier at the top of the stairs instead of giving baby a bath. Suppressing out-of-bounds excursions of voltage is all that, by definition, a surge suppressor does. It might well act as a low pass filter but it doesn't necessarily "clean up" power. I can't see those outlets making a difference in audio quality. But if their goal is actually protecting expensive equipment from surges rather than "hearing a difference", secondary surge protection couldn't hurt. I take it you're already bidding a suppressor at the main panel. I don't think I would like secondary suppression within an outlet.
Joe
