Looking for Sub to pair with Dynaudio Confidence 20s

Hi! 20x20 room, looking for subwoofer pairing recommendations; 20x20 room, fair bit of glass with wood floors. Mostly audio, diverse tastes, will also play video/tv via 2 channel set up. Ideally, not a huge sub. Thanks! 


Thanks all for great input. Given my room, leaning toward the JL E110...


 Im running a Rel S510 stereo pair with my C20s right now in a room 18x15...They just had a price increase so over the 5K bench mark new  but used you could do it..I would not mess with their entry X series..Easy to integrated and no need with all the room correction and  the multi phase chatted about above on other makers.If you want to spend more Id go with Perlisten.