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.