Subwoofer questions galore -- Arcam AVR350 / 2Ce's

OK, I'm really confused! While I'm generally very happy with the 2-channel sound my setup provides (Arcam AVR350 receiver, Cambridge Audio 850C, Vandersteen 2Ce speakers), I listen to a lot of jazz and I'm hungry to add a subwoofer to my system.

I was already to buy a used Vandy 2Wq when I learned that it required a preamp/amp configuration to accomodate the crossover. My AVR350 has pre-outs, but no "main" inputs, so I'm guessing that's not going to work.

I'm considering a used Velodyne DD15 or JL Audio f113 or ???!

But it seems each manufacturer has a different and distict hook-up or integration requirements and/or recommendations...?

To further confuse the issue, I'd love it if my future subwoofer could greatly enhance my Home Theater experience. Although 2-channel is my first priority.

Please... any help; advise; direction, is MUCH appreciated!

Thanks!