Is this for music only...or for HT as well? I tried a STF-2 in a 14x18 room...but not vaulted celing, and it did fine. I think in your room, you may want to step up to the next series of subs...STF-3 or VTF-3MK2. Best to call and ask Ascend.

Of those two receivers, only the AVR330 has 2 zones.

-curtis