Line conditioners, do stabilize voltage, and can remove some frequencies, sense they are basically big capacitors, and transformers.. this is where you would have to go into electrical theory.. so yeah they would do what the guy said, but the only way they would be worth it to you is if you had a large variation in voltage, and your equipment was very voltage sensitive, which nowadays the stuff is designed to work on a pretty large range of voltages, the only way they would make it sound better is through the amps.. as far as the actual signal, most of the time it is digital, so that’s not a big deal, it’s the amp part that will see the difference as the amp will have a constant voltage, so will have a more constant output. Couple of the guys on the board have line conditioners, and one said he didn’t notice a difference at all, he just got a good deal, so he went for it.
On the screen thing, that’s not really that big of a deal, a lot of the screens are “acoustically” transparent. Would be the ideal position for a center channel though, right behind the screen…
