If you are using AC to power your equipment: There IS noise/interference from everything online between your house and the generating station coming in with your voltage. That's just a fact of life. Once that goes through your system, it will either show up as noise on-screen, or in the background of your sound. Usually you are unaware of it until it's gone(blacker blacks/more definition/better resolution on-screen and basically the same descriptions with regard to high-end audio listening("blacker" background, better ambience, imaging, etc.). Like everything else in audio: everyone doesn't necessarily appreciate, or know how to recognize certain improvements/differences and will claim they don't exist. The best thing to do is find a local dealer, and see if they will allow an in home audition. See for yourself if a good power purifier(Chang/Audio Magic/Richard Grey/PS Audio/Bybee) improves your personal experience. Something to read on the subject: (http://www.positive-feedback.com/pfbackissues/0706/magnan.tweaks1.7n6.html)
