Velodyne DD-10, James EMB-100 or Supercube ref.

I have a DD-12, and before I bought it, I listened to a number of other high end subs. In the end, it came down to either Thiel's SW1 or the DD-12 (which cost a ton less than the Thiel). Ultimately, it was the incredible level of control offered by the Velo that sold me on it. I have big time room difficulties, and the software with the DD-12 really helps address them. I am extremely happy, and therefore would recommend that you strongly consider the DD-10. I have not heard the other two that you mention, though, so take my comments with a grain of salt.

I listened to all three subs, and each of them is great...you won't go wrong with any of them. I also chose the Velo DD-12, mostly (also) for the control that it gave me in set-up. Very pleased with the way it plays both music and LFE -- seamless integration with my DALI speakers.