Sorry... away for christmas.
I used to have a Monitor Audio ASW110, which blended pretty well w/ the DC's, although it wasn't really state-of-the-art. At this point I've given up on subs for a while, just so I can get things right within the current bandwidth without trying to extend it.
The write-up in the Absolute Sound's recommended speakers issue mentioned that the De Capos work very well with a fast sub. Scott Markwell, who has used the Royal Virtuosos as a reference for some time, has paired them with the Alon Thunderbolt and the amazing little Virtual Bass Technology Magellan VIII.
Song Kim of Song Audio, much to my surprise, owns one of the the original Reference 3A subwoofers - the size of a large coffee table, using 3 or 4 8" drivers in a sealed box. It wasn't hooked up for listening, but Mr. Kim says it's among the best he's heard. Good luck finding one... Mr. Kim wouldn't take any money for his...