Subwoofer advice

Budget suggestion:
I’m not sure if/how many they still have, but I just picked up an SVS-SB12-NSD (close-out prior model) from ListenUp in Denver for $399 shipped to Texas. It is kind of between their current SB1000 and SB2000.
It is not a beast or able to plumb the depths like my 2 SB13 Ultras in my main system, but it is a nice little add to my 2nd system. May just get another one or two for distributed bass-see above. Been breaking it in overnight(s) with a 30 hz sine wave (youtube) at medium volume for 10 hours at a time; quite the driver workout. Good luck.

Hello pkatsuleas,

     I just wanted to give you a few tips I've learned about getting good in-room bass response over many years of personal research and, probably most useful, personal experience.
    In general, 2 subs will perform about twice as well as 1 sub and 4 subs, configured in what's called a distributed bass array (DBA) system, will perform about twice as well as 2 subs.  It's been scientifically proven, by acoustic experts such as Dr. Earl Geddes and Dr. Frank Toole among others, that any subs added beyond 4 will provide only smaller marginal increases in performance.  This is the reason all in one DBA kits like the Audio Kinesis Swarm utilize 4 subs.
     Atmasphere obviously understands this since he provided this
 link to the AK Swarm system:
http://www.audiokinesis.com/

     Here's a link to an Absolute Sound review of the Swarm which I found very accurate to my experiences using this product in my room and system:
https://www.theabsolutesound.com/articles/audiokinesis-swarm-subwoofer-system/
     This will give you a good idea of what to expect if you decide to invest in a multiple award winning bass system.
     Positioning of subs is critical to obtain optimum performance no matter how many subs utilized. I usually use and suggest using the crawl method (google it for a good description) since it works extremely well, requires no expensive and complicated equipment and it's free.  
     It's also very important to have variable volume, crossover frequency and phase controls on whatever subs or complete bass system you choose.  For best integration of the bass with your main speakers, I've found it best to set the volume and crossover frequency controls as low as possible with the bass still sounding good to you (smooth, detailed and natural with realistic impact and dynamics that you can feel as well as hear.) The phase control should be 180 degree adjustable and set at the position that the bass sounds subjectively best to you.  
     Once you decide which sub or subs you want to buy, I can offer more detailed advice.


Later,

Tim 
    





   

Respectful of your budget, a great value and excellent sub is the Golden Ear Forcefield 3 ( 1000w  18-250hz ) ($549) . I have 2 that worked very well with my B&W802's before I bought my Golden Ear Triton 1R's with built in subs. 
They now are in use in my home theatre greatly enhancing that listening experience. 

Happy listening ! 

Your room is quite large.  I recommend two REL S3 SHO's to play in stereo and to fill space without having to push too much.  I did this in a room 13.5" x 18.5'.

Look also at Rythmik.

Dear @pkatsuleas : Inside your budget and with good quality performance the @instlouis advise is with out doubt the best one.

At your room/system seant position you need only two subs  You can try the Golden Ear units for you can have first hand experiences in your room/system. One advantage in the GE subs is that comes with high-pass filter for the Snell stays focus in all frequencies but the low bass and in this way the Snell IMD ( intermodulation distortion. )  will goes down and this permits that the overall system ( speakers/subs/roo. ) shines as never before. I think you will be satisfied with.

Then in the future and after your learning self experiences with subs you can up-grade it with better quality subwoofers because not all subs sounds the same, exist quality grades in between.

Regards and enojoy the MUSIC NOT DISTORTIONS,
R.