@mr_m - My first sub was (and is) a def Tech PF15. A boomy mess until I got a Behringer FBD Pro parametric EQ. The whole thing was a beast to set up, but the results were, um, okay. But I noticed, once I had flattened out the response a bit, the plate amp was getting really hot to the touch, especially with movies. That kind of scared me. The Behringer is gone, and the Def Tech is for LFE duty only, equalized by the DSP in my AVR. Then I got first one, then another 2Wq, and later the M5-HP crossovers. No comparison. And my set-up story mirrors yours exactly. Easy as pipe.
@bstatmeister - I happened to be at Audio Connection in Verona, NJ, last night. He has the Nines, but they are not hooked up yet. Yes, they look like beasts, although, size-wise, the 7's are large, but not huge. Still, I was surprised to see one 13" driver rather than multiple smaller drivers. I am sure it won't matter with RV as the designer, and perhaps he is feeling the pressure from the competition who usually use one massive driver rather than multiple small ones. I did get treated to a nice demo of the Quatros, though. Johnny Rutan of Audio Connection really knows how to set up a system.