I have a friend that is having problems with his room and wanted ideas on what treatments would help. His bass gets pretty boomy and is the worst problem. He has Paradigm Studio 60s, with matching center and surround speakers. His sub is a Paradigm PW-2200(all indicated as black boxes in picture). The room is 18ft by 12 ft. One of the side walls has an opening that is 10 ft long that is to the left of the front speakers and opens up into a very large room. He has thought of trying to put some type of curtain over the open area in the wall if that is a problem spot. Any ideas would be great thanks.