Rel t9x or Rythmik F12G

@noromance OP is using Klipsch Fortes in a small room. He's already overpowering the room. Be that as it may, and much as I love the REL T/series, they're simply not a good match for the Klipsch. IMHO in an 11X11 room first he needs acoustic treatment and bass traps, then rethink the entire speaker setup. With something more to room scale for both the mains and subs. JBL 4309 and REL T/9x comes to mind.

The Svs sb-3000# are very well built and have tight bass and a great app to control 

and $100off on a pair. Free shipping 5 year warranty and I think a 45 day review period.

Amazing how someone can state "already overpowering the room" without any evidence.  I'm currently using a REL S510, located in my room's primary bass node, which is located right next to my seating position.  Completely invisible with my Forte IVs.  Considering adding two T5's. When properly set up, RELs can be a great addition, without "overpowering the room.?

@ric2001 

You can easily start with one T5 and see what you think.  

I highly recommend Rythmik servo subwoofers, which can probably control the expected low-bass reverberation problems in your small room. They include superior adjustable EQ, which works better than phone-controlled stuff. Your small room does not need two subwoofers

@condosound Other than the fact that I also highly recommend Rhythmic subs there’s nothing else here I agree with. First, the “phone-controlled stuff” that SVS offers incorporates the considerable benefits of DSP (as almost all better subs offer now) and has the ability to control far more than Rhythmik currently offers. That you can do it from the listening chair rather than running back and forth from the sub to the chair is a considerable convenience feature. Rhythmic is just really behind the ball here when it comes to incorporating DSP into their subs. I recommended the SVS subs for their size, performance, DSP, price, and their generous trial period along with their excellent customer support. That said, at a similar price I wouldn’t hesitate to also recommend the OP consider a pair of the Rhythmic L series subs or even better the F series if they’re in budget. Both are larger than the SB1000s, which may be a consideration in a smaller room.

And the size of the room doesn’t determine how many subs are required or optimal, and as most experienced folks here have recommended, two subs are better than one for many important reasons and four are better than two if room logistics and budget allow.