We have added the JL Audio line to our group of companies, and are proud to feature the award winning Fathom F112 in our front room.  This is an amazing piece, easy to setup, great clear directions, and a dynamite Automatic Room Optimization circuit.  It is very fast, smooth, and clear, with none of the boominess or mud usually associated with subs.  I was worried about the integration with the Acoustic Zen Adagios as they have lightning fast bass, but the JL is every bit as fast and just as smooth.  The aspect that really surprised me was how the lower mids and upper bass cleaned up.  These are frequencies not even being reproduced by the sub, yet they are clearer and smoother and much more precise than before.  I have never noticed this before with any other sub.  The only reason I can think of is much more precise reproduction of the lower harmonics.  I am certain this would apply when using the JL Audio in any other system as well.  As an Audiophile, I consider this to be one of the best changes to my system I have ever done. 
Associated Equipment:  Cary Xciter DAC, Cary SLP 98P  preamp (moded),  Atma-Sphere M60 V3 with power supply mods and V-caps, Acoustic Zen Satori Sp. wire, Silver matrix IC, MIT Magnum MA IC, Heed Phonostage, Roksan Radius 5 w Transfiguration Axia, Acoustic Zen Adagio speakers, PS Audio Premier Power Plant.
See: http://home.jlaudio.com/