Had the same problem with my Classe 301 ... worked great for three days and then .... a puff of smoke, a blown fuse and one awfull smelling shorted capicator. When I called the Classe engineer/support he suggested that certain tube preamps can cause a problem with the Classe. I suspected that a speaker cable might have come loose (I had shotguns with two spades per lug so tightening was a problem). Even though I bought the amp used (through an audiogon auction) Classe treated me like with their namesake. Not only did they fix the amp in four days, but they also gave me a new factory box, replaced a stripped screw in the case and paid for shipping back the 120lbs beheemoth back to me. Quite impressive service, considering their warranty does not even cover subsequent owners! Haven't had a problem since.
What I've learned from all this, is that high powered amps are much more sensitive to "mistakes" than their lower power bretheren, and, I now take so called "protection" circurity with a grain of salt. I thus turn EVERYTHING off when making a cabling change or even minor adjustment "back there" and constantly (weekly) check that the amp's lugs and all interconnects are tightened down. --Lorne
What I've learned from all this, is that high powered amps are much more sensitive to "mistakes" than their lower power bretheren, and, I now take so called "protection" circurity with a grain of salt. I thus turn EVERYTHING off when making a cabling change or even minor adjustment "back there" and constantly (weekly) check that the amp's lugs and all interconnects are tightened down. --Lorne