If you want to, "tone it down a little"; Go to a fabric/upholstery shop and get some (loose-not "felt")bonded dacron(http://cgi.ebay.com/Upholstery-Bonded-Dacron-Quilting-Batting-Padding_W0QQitemZ350220762258QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item518ac8bc92&_trksid=p3286.c0.m14&_trkparms=65%3A12%7C66%3A2%7C39%3A1%7C72%3A1205%7C293%3A1%7C294%3A50). You can experiment with different densities, by rolling it tighter/more loosely, and damp the port to your tastes. Most other suggestions will turn your cabinet into an acoustic suspension design, and completely ruin the system designer's alignment. Have you tried lifting them off the floor and/or moving them away from any corners?