Just bought a 20-39PC+ and received it today. Set it up as per instructions and calibrated the system with an SPL meter. I am very dissappointed. At higher volumes I can detect an audible rattling in the cabinet with CDs and radio. I can't locate the source but it is definitely coming from the subwoofer unit. No lose fittings around the woofer itself. It is not through the floor or walls either. I contacted the SVS tech staff and am waiting for a reply. I am so upset. I've been waiting all week and now may have to send it back. Any ideas on what could be wrong?