You should get an active sub. It will take some of the strain off of your main amp. If you have a preamp, you can use "Y" cables. There is no such thing as fast bass by the way. I know this will cause a lot of arguments. But consider, all things that produce bass are larger and slower. If you cross the sub over at a lower frequency, it will blend much better.
Subwoofer Question: Active or Passive?
Looking for most musical sub to fill the lower end of my Totem Arros. My budget is $500 at most new or used and my stereo amp does not have sub out. I need quick fast tight bass and read, most likely 10" with good amp should suffice. Should I buy a active sub or a good amp and passive box seperately from Audiogon or Ebay. Please give some brand recommendations