The Descent is badass. I've had this sub (matched with my Martin Logan Aeon i's) and they are a beautiful match. But just speaking on the Martin Logan Sub; its pricy but if you're looking for a top of the line, fast, knock a hole in your chest subwoofer, you gotta hear it to believe it. I'm sure somewhere on this earth there's a better one but let me know when you find it.
_________________________
Outlaw 990 & 7700
OPPO BDP-93
Panasonic PT-AE7000U 3D Projector
Direct TV Set top
DA-Lite 120" Screen
Panamax 5400EX (Filtering System Components)
Furman M-8 x2 (Filtering ML Fronts, Center & Subs)

Martin Logan Aeon i (Front)
Martin Logan Theater i (Center)
2 Martin Logan Descent (Subs)
Monitor Audio (Surrounds)
800 Watt Buttshaker Amplifier w/6 Bass Transducers

Accessories:
Cardas, Kimber Kable, Blue Jeans Interconnects
Naim Audio Speaker Cable
Toslink's
DIY Sound Panels | Bass Traps
Logitech 1100 Remote