I can't speak for everyone else- but when I say it sounds clean, I'm referring to sound quality. I hear bass with texture when appropriate, and bass that is smooth as silk when appropriate. I owned an HGS-10 up until a couple of years ago, and an SVS PC-Ultra up until a month ago. The PC-Ultra (again, not the current one ) was great for movies, decent for music; it did not have the "stop on a dime" control that the Velodyne had- especially evident in mid bass in most music.
The effortless control over midbass that the Tower exhibits makes my old PB12 sound sloppy too. It's something that I 'knew' was missing with the the PB12 since I have a few other DIY sealed subwoofers, but now that I've got the Tower its very clear that something isn't right or lacking with the upper bass region of the PB12. The Tower is much more articulate in that region not to mention it hits lower than the PB12.
Having heard many of the same subs as metioned, I always came away shaking my head with my referance for SQ ability being DD's and HGS's as well, and while I have heard talk about the potential for musicality in these overbuilt, big, ported units, I have never heard them close enough in musicality to warrant getting the extra output and depth for the trade-off in sound quality across the board.
It's funny that some of those that never would acknowledge a difficiancy before seem to be experiancing the differance now.
The Conquest, OTOH, sounds cleaner, plays much louder, much lower, and exhibits that effortless control over midbass that the PC-Ultra could not ever muster- very similar to the Velodyne. I never thought I'd say this, but the PC-Ultra sounded sloppy compared to the Conquest.
I really hope that this might be the company that builds to satisfy every need - hopefully , even builds some of 'em smaller too , at some point.