I've got 2 RANE crossovers, an AC22B active crossover, and a Stereo 2-way crossover. Right now I'm using JBL 4326 monitors.

Can anyone explain if using either one of these makes a difference? I tried to read up on what crossovers do, and it said something about it distributing the right frequencies to the right components (the sub, tweeter, etc) which makes the frequency response more accurate. I was told buying a sub wasn't really necessary for mixing, so i didn't. I've got these crossovers just sitting here (leftover gear from an old DJ setup of a friend) and I'm wondering if I should try hooking 'em up. Anyone care to throw in their 2 cents?