Well it sounds like a very large space. In fact, based on your numbers, if i got them right, you have approx 4,600cubicft not including the leg of the L. (where the pooltable will be) that makes for a very large area for the sub to fill.
Unfortunately your budget is not going to allow proper pressurization of that room. $600-$800 will get you a nice sub but in order to get great bass you will need to add a second identical sub down the road.
Fortunately you arent looking for a lot of bass though & your expectations seem reasonable. Thats good. I would highly consider going the DIY route. If you or a friend have some woodworking skills then you can actually get some pretty incredible bass & stay in you budget. Let us know if that seems a direction youd be willing to take. My friend & i are building a sub with his $400 budget & from what ive read, we are going to end up with a sub that is equal or better than the PB-12NSD. Just a thought for you!!
If you dont plan on adding a second sub or building one yourself then my recommendation for that space is hands down the VTF-15H. Its just north of your $800 being at $879+ship but if you could save a tad more it would be well worth the wait!!
I have my 15H in my livingroom theater that opens up to other areas. The total space is 8,600cuft. Thats huge for it! Yes i have an MBM-12 handling the mid-bass but the 15H just has such a great amount of output & never distorts or bottoms out. For music i only use the VTF-15H, i turn off the MBM & only use that for movies. With music it sounds fantastic!! I never would have thought that a ported 15" could sound so clean & musical. But hey, its designed by Dr.Hsu so i shouldnt be suprised. I am however going to add a second sometime down the road. Not that i really NEED it, just WANT it
I think dual Rythmik FV-12s could sound decent as well. Wont be as much output or as deep as the 15H but placing dual subs correctly will even out the bass across multiple seats for more than 1or2 people. But again that totals about $1120 shipped. But you could get one now & put the save $300 towards a second one later.
One thing about the NHT subs is that they are sealed. This is not very ideal for home theater & since your room is soo big they just wont have the output needed for you. Even the B12D wont do it. If i were in the market for a sealed 10" or 12" id be looking Emotiva instead of NHT. But you need way more output, headroom then those subs can give you. Its just the nature of the beast & the laws of physics & moms home cookin!!...forget that last one!!
Please calculate your total cubic foot of your basement for us. (WxLxH=CuFt)
Let us know if DIY is an option as well.
We'll get you dialed in sooner or later!!
