I've been looking for a crossover for quite a while now to use with my passive sub. Since I really only need one channel, I've looked at single channel crossover kits from Marchand, the Outlaw bass management box, Rane etc and I keep coming up with the 10B being the best all around value, at least for my needs. I haven't bought one yet although I hope to be able to trade in a 3B-ST against the cost of one at my local Bryston dealer. You might want to take a look the 10B if you haven't already.