I know this is a simplified response to a more complicated question.....I don't know how other people's line arrays are set up but I can handle this by adjustment of the system. I have a pre-amp which feeds the analog electronic crossover. The crossover feeds the three ranges to three separate power amps. The tweeter and the bass power amps have volume controls on them.
This allows me to adjust the intensity of the treble above 2500hz, and the bass below 165hz. When I have a recor4ding with too much sibilance then I turn the tweeter amp down a bit. When I have a recording with too much or too little bass, I adjust that too. Often rock benefits by increasing the bass end a bit, and classical by reducing it.
This is sort of like equalization, but without the same phase issues, I think.
Can others not do this? I made sure that the power amps I purchased had separate volume controls. It also meant that I didn't need to push to less expensive op amps of the Rane crossover too hard, and let the much more quality in the power amps do the job. If you can't find power amps with volume controls, you can always buy a control amp and use that instead. In fact, my tweeters are run out of a 60 w/ch receiver.
Marlboro