Just caught up on this thread. Like the direction you guys are going in, but agree with Maz in terms of stepping up to a sub suitable for the room size. Our friendly OP should look at starting with one sub suitable for the room, then plan on adding a second down the road a piece.
Outlaw X-13, Monolith 15", VTF3 mkV HP or VTF15H mkII, PB3000... (no particular order).
That said,
@Tony Cardenas , I know you mentioned some measurements above, but it sounded like maybe there is still more open room that you didn't account for. I don't argue that you need to attempt pressurizing the complete open room volume, necessarily, but the physics behind those Low Frequencies are such that all that open space will eat up some of your bottom end.
By getting the right sub for your room size, you help make certain that you don't peter out in the moments where you want it to be strong.
By doubling up on them, you gain a little output presence, as well as smoothing the performance out across your listening area. Both of these are good things.
Moreover, you also ensure that you maintain adequate headroom for your subs to really stretch out when they need to during the most demanding peaks in your favorite movies or music.
Anyway, the Dayton Sub 1200 is supposed to do pretty well for a budget sub, and by the review I know, it performs on par with the 15" version... but if OP wants an upgrade, then I encourage shooting for a real step up.
The proper subwoofer investment will last our friend a good long time with no regrets.
Don't be bashful.
