I have an MJ Acoustics REF100 in a 20 X 25 living room and it sounds wonderful and plenty powerful for music with my floorstanding Dynaudio Focus 220s.
The MJ Acoustics sub opens up the sound of my floorstanders and changes them into sounding like speakers that came with very tight, authoritative, and musical 10" woofers.
I had a Velodyne SPL-800R subwoofer (the supposed winner of a shootout with the MJ) and didn't like it and sold it because it wasn't musical enough for me. In fact, I have tried several subs including a Velodyne HGS-11 and a Martin Logan Depth sub and sold them because they stood out like a sore thumb on certain musical passages and didn't integrate well. No so with MJ Acoustics subwoofers. Unlike the others, you don't turn it down to get it to blend in with music, you turn it up and let it sing. I will never play music without my MJ Acoustics sub again. I am so spoiled my Dynaudio floorstanders now sound weak and inadequate without the sub. They give you the perfect "Wow, thats what music is supposed to sound like!" No, the MJ is not the best Dinosaur stomping sub around but it is adequate when you turn it up for home theater. But for listening to music and integrating with your speakers, the MJ Acoustics subs are PURE GOLD.