My setup is nearly identical to yours (really!) I use the polk sw. If a new cable doesn't do it - must be the receiver but I would be surprised. This Pioneer is fantastic. Have had this model going on a year and it's sounds GREAT. I know the manual sucks but check your settings. Use the on screen setup functions (has a speaker setup and sound check) or find a DVD with a THX or similar sound optimizer included with the movie. I'm betting your problem is the cable sorry to say.