I play my 6000 from 75 to 85 for hours without overheating,I was driving them with a 500 and 518 so no calibration other than drivers calibration in the 6000 which in my case is at 0 for all.

Before I replaced the tweeters I could not play them higher than 78 for more than 20 or 30 minutes.It also was dependant on the ambient temperature.(Florida)

I am now using them with a 500,518,561,5000c and enjoying every minute.(At 85 or more).