If I count all the connected space, my room is 8,812 ft^3. It's a very ugly space for HT. The living room, which is my HT room, has a vaulted ceiling, it is open to the dining room, which is open to the kitchen, which is open to the family room, which is open through a hall back to the living room. On the left of the living room is an open staircase to the second floor. My sub, an SVS PB12 +/2, is located on the right side, about mid way between my right main and the LP. I sit 12' from the screen and about 5-6' from the sub. The sub actually sits on the fireplace hearth. I use 4" rigid home insulation to close up the fireplace.
My living room/HT has a large volume due to the vaulted ceiling, but not much floor space. I have to leave the left side open because it is the main thoroughfare. I have a 65" Mits RPTV. I have a huge entertainment center around it (my wife's requirement) that takes up the entire wall. I can't get tower mains because there isn't any floor space. I have Bose (I know, this is my next upgrade) 301 bookshelf mains, a Bose VCS-10 center, and Bose 161 surrounds. These will all get replaced this year with Axioms, Ascends, or SVS MTS-01.
I had not used the 16Hz tuning on the +/2 until last night. I did notice some lowering of the overall SPL (didn't measure), but it did seem to bring in a little more bottom end (not measured). This did not reduce the impact of the whole sound and I'm sure I have enough headroom that I can increase the gain if needed.
I have not EQed the system. Still trying to decide if I want to go SMS-1 or BFD. I have no bass treatments. I do get some boominess at a couple of freqs. But not enough during movie playback to bother me. It is more noticeable with music, but I rarely listen to music anymore.
I haven't calibrated at the 16Hz tuning. I just paused the movie, threw in a second plug, and changed the low cut filter.
I will try to get time to do some A/B comps of a scene between the 20 and 16Hz tuning and see if I really hear what I thought I was hearing. It's difficult to really tell the difference when you can't just go A-B-A-B, but have to go A, stop, make changes, B, stop, make changes, A...
I don't know how Craig has the patience to run the shootouts when he has to change out whole subs. Must be exhausting.
Sorry to ramble. Too much? See measurements below.