Hey Pote, I have a buddy with a huge space as well. I would guess that his is larger- more like 10k cubic ft. He bought a single VTF 15H that ended up being more than enough for his needs. You might try one of the large subs tha you're looking at and see how it works out for you. Pressurizing a space that large may prove difficult, so why not try one for starters and see how you like it.
cheers, Mac
i would have to strongly agree. getting the subsonic lows with a large sub will get you there. but, since most music occurs north of 25hz, it can get overkill really quick if you start doubling up. you do watch more movies than music, so... kinda of a judgment call there for how deep you want your sub to dig and etc.
listening proximity (how close you are to the sub) is also a factor, going to two units can help fill out the sound within the large space while giving you room for more bass, because that is what usually happens... we all want more, more, MORE!!
Funk Audio is way up there in sound quality and has a tendency to image really well and blend into existing systems with very little effort. the powered units have tons of dynamic headroom which does help with the overall execution of source material. with funk you are buying a piece of art that can throw-down and make you feel violated. the new remote dsp setup service they are working on can make your sub perfect no matter what room or layout you have going on.
HSU is really good. excellent reviews, and top notch service (says the reviews). i dont have any experience with them so i can't speak first hand, but i did read that at extreme levels one guy reported some port noise... but that was running one sub half to death. they sound like a really ballsy sub with lots of grit. the advantage of dual subs is that there is lots of change left over, you can always pour more on when you want to unleash the beasts. the drawback is that you have lots of real-estate invested, and set-up can get challenging if you let it.
I am have a strong opinion of svs and its hard not to voice it without sounding like a knob, so I'll just keep my mouth shut on that one.
What I would do: contact all the manufacturers you are interested in and give them the scenario (room size, existing system, listening habits, etc) and ask what they would recommend, then go with your gut.
good luck and may your life be rich and full.... of bass.