I have a lower-end surround sound system. I get great sound from DVDs and CDs, as I have both a CD player and a DVD player hooked up to it. However, when playing surround sound TV programming, I hear a slight hiss in the background - which is annoying - and do not notice the effect as much. Is this normal? If not, I'd be happy to provide any other info needed to fix it. Thanks for your advice.