Which subwoofer?

I have a small room (10’x14’) and am wondering if a subwoofer would help. If so, which one?

I have Martin Logan electrostatic speakers with  8” powered 200 watt woofers and 8” passive radiators.  The bass is articulate, but not very deep. I am wondering if I could get more bass volume and depth without loosing detail with an additional subwoofer?
I have tried an 8” Velodyne, but could never integrate it with the Martin Logans so I sold it. 

The Martin Logans are powered by a 200 watt McIntosh receiver. 
Any thoughts?

The REL looks interesting, but I have what is probably a stupid question. The REL t5x goes down to 32 hz and my Martin Logans go down to 34 hz. Will I notice the additional 2 hz of bass energy?

Thanks for your responses. 
@kenrus , you wont, its the quality of the base rather than 2hz either way that matters most.

How about looking at used ML Descent i’s , I recall a number hitting the classifieds when the newer models came on line.

Very good quality and reputation also offer a lengthy trial period along with free shipping TO and FRO. 

Post removed 
I do own a couple of great but older REL subs (B1, Storm III) but recently acquired three sealed SVS subs, one SB-3000 and two SB-2000 subs (close-out). I'm very impressed with the modern technology.

I owned SL-3s as main speakers for 16 years (still have them) and if your bass quantity is sufficient from your MLs then I'd try to cross very low to add clean deep bass (usually low volume as well) to what you have for a more grounded presentation. Good luck!