Using 2 Subwoofers

2 subwoofers are better than 1 as 3 are better than 2 and 4 are better than 3.

The most common misconception about multiple subs is that is will be too loud. The truth is that multiple subs reduce distortion and take care of multiple room modes which is trying to make bass even around the room.

Some people are lucky and get excellent bass response in there room with 1 sub but that is not common but rather the exception. You will have to experiment in your room and find out what works for you.

with a room that size-
get one and be done with it-
get a used JL Audio 112-
you will thank me later.

Buy two, try them out, then try one and if not much difference, return one. I have two and gave the dual set the edge. The only way to nail the issue is to actually have the two initially. But remember, placement is everything.

I second the JL Audio brand recommendation but I think (hear) that bass is stereo, too just like the rest of the spectrum. I use a pair of JL F110's and love the sound. Had one larger sub before these and two are definitely better than one for my system. When I got them I unpackaged them, put them in place, used the auto room optimization, slightly repositioned them once, and was done. Just like that. In my experience with two you can run at a lower level which makes them easier to integrate and avoid common sub issues.