Several members, including myself, have done 4430 active biamp according to JBL specs using the JBL card in 5235, and gone back to full passive.
Here's the N3134 passive-only charge-coupled (biased) crossover I built, so you can get an idea of what it is as implemented by the Zilchster:
It's been tweaked a bit to run the different HF system shown.
It's still biampable, but that requires two batteries, ideally, one each for HP and LP....