I just bought a Yamaha RX-V573, and it doesn't seem to get along with some of my (6.1) speakers. These are speakers that all worked fine with my previous Onkyo receiver. When all the speakers are connected, the unit will play sound normally for a minute or two, then will start buzzing, and then shut off. If I disconnect both the left and right surround speakers, it works fine. If I disconnect just the left surround speaker, again it works fine. But if I disonnect just the right surround speaker, the problem happens. This made me think that there was a short somewhere on the left surround speaker wire, but I've used several different wires, including banana plug wires, without fixing the problem. I've also tried connecting the right surround speaker to the left surround speaker terminals on the receiver, and the problem still happened. At this point I was thinking that the unit itself had some defect with the left surround speaker terminals, but as a last test I tried plugging the left surround speaker into the right surround speaker terminals, and the problem happened again! To summarize: Left speaker + left terminal = buzz Right speaker + right terminal = works Left speaker + right terminal = buzz Right speaker + left terminal = buzz Any suggestions on how to fix this? Or does it sound like a defective unit?