I just bought a AVR505. Hopefully someone out there has either this model or the 507 because I am having a problem. I am getting a slight bit of feedback and a whole lot of popping. The front speakers pop, whenever I change a channel or increase the volume. I don't know what the hell the problem is. I checked my connections and they seem to be proper. My TV has a digital coax output for audio and my dvd has a optical out. Both of them have done this. No problems with video. Please help me, or suggest a solution.