Hello Roy. You didn't mention what your budget is for a sub, so I'll offer a couple of suggestions: I've had an SVS SB-3000 (13" woofer in a sealed cabinet) and it works well with my ESL-X speakers in a similar sized room. The SVS app is a joy to use for controlling sub volume, crossover frequency and such on the fly right from the couch. I can't imagine have a subwoofer without it. A friend has two SVS-2000's he uses with his Klipsch RP-8060 tower speakers. If you have the budget and the room for two subs I highly recommend it. I've heard this setup and the bass is clean and deep. Good luck.