What has blown my tweeter????

It's not clear what you mean when you say the tweeters have totally disappeared. If they look normal but just aren't playing, you could have a component failure in the crossover or a bad wire connection inside the speaker. Or you could just have a poorly manufactured tweeter that failed after some use.

If you really mean that the tweeter is no longer visible to the eye, i.e., that it has been physically removed, then it must either have been ejected across the room or have fallen into the speaker enclosure. The volume settings you described are unlikely to have caused this. Was there a thunder storm? A close lightning strike can do weird things. Otherwise, I would suspect foul play. I assume the tweeter was in place when you got the speakers. When was the last time you observed the tweeter? Do a lot of people have access to your listening room? I hope you find out; good luck.

If you suspect the Cap 101, I would try switching channel connections and listening at low volumes to see if the high frequency noise is recurring (don't fry your other tweeter!). If you can isolate the source of the noise to the Cap 101, I would write a description of what's wrong and send it into the factory for repair. I assume it's still under warranty if it's brand new. Unfortunately, you may have to pay for a new tweeter; I doubt you can get Classe to pay for the collateral damage. The new tweeter may sound significantly different until it's broken in.