It seems the room size is also a concern for the OP.
My room is (10 x 14) minus closets. Tried several subwoofers of different sizes, configurations, etc.
I couldn’t get any of them to just add bass without things sounding muddy. I pulled everything out of the room to lay down carpet. Perfect opportunity to test the subwoofer anywhere in the room.
The carpet helped a bit but it still sounded pretty bad.
My DBA order came in stages. Two subs arrived first. I hooked up just one of them, listened, played around with the crossover, gain, etc.
Didn’t sound good. Got near acceptable results in my listening chair after moving the sub around.
Hooked up the second sub, listened, played with knobs, ...
I never had more than one sub so was very curious to listen for any differences.
The 2nd sub made a big difference. Less muddy. A bit faster.
It actually sounded pretty good. This, I could live with. Easily.
A few days later, the 3rd and 4th subs arrived.
2 subs are up on heavy duty steel wire shelf units facing the ceiling.
1 sub is on a long shelf on the wall behind me also facing the ceiling.
The last sub is on the floor next to my desk facing forward and supporting a nice lamp.
I look forward to hours (days?) tweaking the sub positions (especially different heights for the ceiling subs).
It was suggested by Duke at AudioKinesis to try varying the heights of any ceiling facing subs as this affects dispersion in the vertical plane.
But even after muscling up 3 subs to their respective perches and putting the 4th sub down by the desk, no placement tweaking as my back was protesting, the bass sounded great.
Didn’t play around with ports, polarity, phase,...
This is very noticeable. I now can hear cellos, tubas, trombones, bass guitars, etc. with much greater detail.
It’s like hearing more "things" on your favorite record on a "better" sound system at a store or show.
But now the more "things" you hear are coming from the bass frequencies.
Further, multiple subs, properly placed, will open up the soundstage.
My little Maggies (LRS) make the room sound larger.
The subs make it sound even larger but also more full.
The effect is really amazing! Actually regained more space in here with the shelf units!
OK. Do you really need to go for a DBA?
Or will adding just a second sub do it for you?
For now, I would just add another sub. Spreads the load. Evens out the bass.
As millercarbon indicated, don’t worry about "matching" the subs.
See if you like it (2 subs vs 1 big sub).
Do your research. I did and found the science behind it supports why rooms (especially smaller rooms) benefit the most using multiple subs.
Then, later on, borrow another sub or two to experiment with.
If you like it, you’re just a few subs away from a DBA.
And yes, 4 subs will rattle your windows!
