I have a 5 piece logitech 540 5.1 speaker system with a 6th piece subwoofer. Anyways, the two rear speakers seem to garble background music of the songs when in the "Matrix" mode. Is that natural? The system came with three cord-jacks, but I only need to plug in the green colored one into the laptop for the system to play sound. Is there a way that I can configure the rear speakers to play normally? Or is this natural?