By the way, have you thought about just using a passive line level crossover (PLLXO)?
Here's a couple good bit on it: http://www.silcom.com/~aludwig/Sysdes/Crossove_Design.htm#Bi_ampingAnd, http://www.t-linespeakers.org/tech/filters/passiveHLxo.html
In my mind, whatever keeps op amps out is a good thing. Of course, many will disagree, so YMMV.