DC crossovers? General opinion when I looked into it was there is not much point. Good quality compoents, no electrolytics to dry out and the level controls are designed in such a way as not to degrade the sound (within reason presumably)
Lockwood suggested getting rid of the plugs on the speaker chassis and hardwiring the cable but that was about all.
One big improvement however is to remove thm from the cabs, a good move in my case. I am hoping to offer a case to house the crossovers at some point this year.
HTH, Paul.