Active crossovers

Sorry guys. I've been away. I hope this thread isn't dead. I have to apologize as I'm out of the loop in regards to this entire conversation and completely illiterate to the jargon. I have a pair of JBL 2440 compression drivers with horns and Hartsfield lenses, a pair of JBL C1200(12") mid-bass drivers and a pair of JBL 2245H(18") bass drivers. I want to cross the 2440's over at 700hz, the C1200's at around 300hz. I have the specs and requirements for the drivers and intend to build the cabs. Efficiency for the 2440's is 117db, for the C1200's 93db and the 2245's 95db. I just love the sound of the Ampzillas and have a bunch of them. The best ones IMO are the Son Of Ampzillas at 80w.min. per ch. I have three that are rebuilt and want to tri-amp, hence the Behringer. But it would be great to be able to use just one amp without the need for a passive crossover. Another question I have is whether it's possible to install a fixed resistor in conjunction with a lesser value bias pot in an amp in order to achieve a finer adjustment since you would now have a larger space of adjustment for the
wiper to rest on the pad. Multi-turn pots are such only because there is a step-down gear attached to the adjusting
screw but the actual pad is the same relative length as any other single turn mechanism. It simply allows you to arrive at the adjustment more easily but does not improve it's ability to hold the adjustment. It seems a wider place of adjustment on the pad would accomplish this. Is this a worthwhile exercise?

With a line-level xover you will always need an amp on each channel. More specifically, you need amp inputs on each channel. I say that because a multi-channel amp would only work if it also had independent inputs on each channel.

I use 2440's, EV15b mid-bass, and JBL 2240Hs for bass. Tweets are fostex t500amkii's. I used a different approach. No digital crossovers or amps though. Two, Marchand analog xovers, a couple of ~70 watt PP, and a 500watt SS amp. The tweets run with a simple cap off of one of the PP amps.

I am a little confused by your question regarding the resistor. You say these are bias pots (?) but I've not heard of stepped biasing. Are these stepped attenuators?

This is a question regarding bias pots in general. My experience has been that they don't hold their adjustment for very long. This is the case for all the amps I've owned. They may stay close to the mark, but still drift. The issue is not that they drift per se, but that they drift to different values from each other so that you lose channel balance, whether you're dealing with monos or an integrated. I'm speaking strictly of SS amps here.