I don't want to get into the whole "placebo effect" that was started in Mike Knapp's thread, but I have to report my personal "butt dyno", as we call it in the car community, ie; can the seat of your pants tell if there is a difference in the tweak you made to your car? How much of a real gain before you notice it? Anyway, I had long been using a basic, $10 surge suppressor for my system. Over the past year, I have been upgrading basically every piece of my system, so I figured I should have at least decent power protection for this gear that I have spent time and money on. I found the 4300 for a good price, and bought it. I was looking for nothing more than piece of mind WRT surge protection. However, I have noticed an improvement in sound as well, which I had no expectation for at all. It is a very subtle, but noticable difference to me. There is definitely a reduction in backround noise, but that is not all that I feel I am hearing. It is not easy to describe, as I am not sure if I am hearing "clean" power, less noise, or more focus, but it sounds different to me. I've only sat with it for a few days so far, but I will do some critical listening again, to see if I am really on LSD or sugar pills.