I used a Marchand external crossover when I biamped my Magnepan 20.1's. Great flexibility when adjusting frequency crossover points. Check out his website
Recommendations for Electronic Crossovers - HELP
Dang, I am biamping my B&W 804 matrix speakers using a 200 watt for the woofer and a 50 watt per channel for the top - I have looked everwhere and cannot seem to find a decent outside crossover that does not cost an arm and leg. Wasted a lot of time looking at stuff meant for a PA system! I am not looking for a kit either. Please help. Thanks!