Here is something I wrote to someone else a while back on the 12D:
I am totally in love with the 12D. We have what you would consider a large room. I use it with 4 5B and a 5C, with an Onkyo 805. Setup was pretty simple, however I have yet to use the sound meter. I did it all by ear, and I am very happy with the outcome. One of these days I will get around to seeing how close I am with the meter.
I use this at about 90% movies and TV to 10% music. However, some of those movies are concert DVDs. I have no basis of comparison, as I took the 12D without doing a side by side to another sub. I was considering a AV123 15" sub, but the waiting list was 3 months at the time.
As far as "feel".....oh ya man, you can feel it. When auditioning some other systems before I decided on giving Aperion a try, my wife was liking something called but shakers, or something like that. After watching our first movie together, and feeling the sound....she said "who needs those but shaker things!" I live in California, so most of our loose items are held down with earthquake putty. Thank goodness, because I certainly would have shaken some stuff off my shelves without it. One of the first movies I sent through these speakers was Terminator 2. I was IN that movie, totally immersed by all the sound effects. Then one night, when wifey was out...I watched Batman Begins...at pretty much max volume. I thought to myself, "this is better than a theater". And it is!! Concert DVDs are an incredible experience. You really feel that you are at the show. I had a friend over, and we were watching a Yes DVD pretty much maxed. Clean and clear is what I would describe it. My friend said he had no idea how loud it was until he tried to talk to me while it was on. And that....is the desired effect. Good and clean should never feel as loud as it really is. Maybe that is kinda dangerous now that I think about it.
Scottiemon