iirc, my three.1 had a switching function for 2-way with ft/rear hp, and sub lp, but i don't remember if it would do 3-way, though it does not sound like you need it anyways. i sent all the original paperwork with it lnib. i would start off letting the three.1 do the crossing over and then fine tune at the amps, if you need it. listen to it both with and without the subs playing to see if the mids extend too low. i thought it was a 70hz cross, but could be wrong. too many settings for me to remember on all this equipment, lol. anyways, the preset frequency on the three.1 might be good, but if you need more adjustment, then i would go to the amps and switch them into thier cross-over modes to find out. just be careful of the sensitivity on those amps, because the three.1 is capable of feeding them as much as 11.5v to the rcas, iirc. the higher voltage does allow the amps to pick up less noise, but just be careful not to let the gain feed too much into the amps.