I've been using a Panasonic amp with my home theater setup. Sometimes, at certain bass frequency, my left and right speaker's tweeters makes this bad buzz. I am using KRK's studio monitors for my 5.1 setup. I have replace both tweeters and replaced both crossovers in the speakers. I have also replaced the speaker cables and the optical cable from the DVD to the amp. I still get the awful buzzing noise from certain DVD's. I don't know what else to replace other then the receiver. Could it be possible that the internal crossovers inside of the receiver aren't working as they should? Thanks!