HELP: Subwoofer for SET setup

Does an SET setup with efficient mains need a special kind of subwoofer for a good match or will any good subwoofer that work? I think any good subwoofer should work if I pass the subwoofer a good signal, right?
I think if you get your signal from the amp's speaker binding post, rather than the from the phono out of the pre-amp you'll be set. There is most likely a better way to describe what I mean, but i have a SET amp and had the same problem, switched from a Audio Pyhsics to a REL and have been a happy camper ever since.
You should match the speed and sound of your sub to your main speakers. Use an electronic crossover and set it at the correct point and slope for integrating with the main speakers. Make sure that the sub will go as deep in the bass as you want to go. I've seen many subs that only go down to 40Hz, and that is not much of a sub. To drive it well, you'll need some good strong power, as bass frequencies require alot of power to get high SPL, and most subs are not real efficient, and some have equalization built in, which will need even more power.
Try a REL Strata sub; works great with my Audio Note Conqueror SET amp and Audio Note preamp.