Using 2 Subwoofers

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.

Bizango1,

Bass below 100Hz or so become nondirectional. If you can hear the bass from the sub, either your crossover frequency is too high or the sub generates too much high order hormonic.

Sidssp,

I am aware of all the tech reasons you're referring to. In my room I can't place the sub in the middle because there's a large aquarium smack in between the speakers (has been for the last 35 years in a number of homes). With a single sub on the left or right I didn't necessarily hear the sub but with stereo subs I DO hear a broader and deeper soundstage particularly with classical music. I "know" the rules but I "experience" the effect of stereo subs-it sounds wonderful.

My room is very similar in size to yours, and I find my single Velodyne F1500R is more than enough bass. Location is on one side, in the center it did not produce much bass. My main speakers are ADS 1590/2's, full range in their own right. But still the sub is needed. I can't imagine sticking 2 subs in a room my size!