I have the Polk rm75 5.1 speaker set combined with a yamaha rx-v571 receiver and a Polk pw10 sub. After about 5 days the center and left channel speakers started putting out a loud buzzing sound. This only happens when BOTH wires are plugged in and it doesn't matter which side (+ or -) the wires are in. I have tried new wire and tried changing the connection at the receiver itsel but I still get the buzzing sound. It happens immediately after the receiver is turned on. Not reallysure what to do and Polk support is only open mon-fri.