WOW!
This is the best subwoofer in the world, no contest. I've auditioned the REL Studio III, the Velodyne 1812, the Velodyne DD18, and this smashes all of them.
Price correction: MSRP is now $12,000. I got a special deal for less.
I also own the top-of-line Sunfire, and two B&W 855s. The JL Audio Fathom f113 gets an 'A' rating from Stereohile. THe Gotham makes them all look like a joke.
It's expensive, but this is the last subwoofer you'll ever buy. That's why I bought one.
This sub is very musical as well as being unbelievably powerful. It sounds far better than the Sunfire, and comes close to the B&Ws in musicality.
It's impossible to stress out this sub (that's been my complaint about other subs). My only real complaint is that it doesn't go much below 20hz. It's pretty solid down to about 18hz, but below that it really falls off.
I've owned lots of really high-end subwoofers, and this makes all of them combined seem like a joke. I tell my friends it's like owning your own personal atom bomb.
The only downside I can find is that everything on bookshelves has been falling onto the floor. And I worry about my foundation, literally.