yes if you cut all power to the tweeter but shutting it off (full counterclockwise) it will over heat the crossover which will cause it to fail. it has nothing to do with your eq, what you are doing is fine. you can keep it slightly on and its ok but don,t run it full off
I've heard the same thing, but never experienced it. If I didn't want any high end from my cabs, I'd get cabs without tweeters.
I've got a Shuttle 6.0 powering Avatar B210/B212 neos, I leave the EQ on the amp almost flat (bump up the bass just a touch) and set the tweeter control on the cabs to about 45% (11:15ish
5sg.

