http://www.hometheaterhifi.com/volume_11_3/paradigm-seismic-subwoofer-8-2004.html And did I say small? I could easily stack three of these and still be under the visual load of one SVS tube. I hate to throw around some crazy adjectives, but these puppies rock. There was a clear brute force difference between the Seismics and the SVS CS-Ultra's. In fact I really felt like one Seismic was a little stronger than the SVS pair. If you remember the SVS-Ultra's were louder and almost as deep as the venerable Velodyne HGS-18. So putting the Seismic in comparison, it will knock you socks off. They have a very clean authoritative sound, they never once shut off during my torture test. Where my Ultra's bottomed out, the Seismics played through. I was skeptical, as I had heard a few "compact" and "loud" subs, and well they didn't sound very good. Paradigm has really hit the nail on the head, very compact, and yet sonically clean. One Seismic stronger than the SVS pair and the Ultra bottoms out.