What crossover for stereo subwoofer?

I am looking to buy a crossover for my sub which is a dual
16" woofer bin box design.It is powered by mono amps thru a preamp which is SS .I want a solid state crossover that is 2nd order -12db down.So the ?? is which one best fits my budget $500-1000, and is clean sounding that doesn't impart much in the chain.The inputs and outputs will be RCA'S.
Active crossover
Any suggestions and comments are appreciated.
I'd recommend this Behringer DCQ2496...it will let you experiment to get the optimal bass management you need.
If you're patient, a used Bryston 10B sub may come up in your budget range. Reliable and very transparent.
NHT X2 filter: http://nhthifi.com/current/products/speakers/x2.html
I took a look at the behringer and it really looks interesting except I need RCA connectors.

The NHT X2 looks to be just the ticket and is available for 299 which is a great price.

The Bryston I have to look into.

A friend is using the X2 with Pass Labs X1 preamp, Parasound JC-1 amps, and Martin Logan SL3 + ML sub. He's very happy with it. In his case it let him run balanced lines from source to amps. I'll also suggest that with the left over $$$ you might look into a Velodyne SMS-1 digital PEQ. The same friend bought mine and loves it.