Vintage tube amps blowing tweeters? Speaker protection?

I was just talking to a friend of mine who has an old McIntosh tube amp. He stopped using it because it quit working. He told me that the amp "toasted one of my tweeters". Basically, I guess the amp started making some static and popping noises and fried his speakers. He said that what he did as a precaution was he installed a fuse between the amp and the speakers. This has got me kind of spooked. I realize that vintage amps don't have protection/shut off circuits. Is it a good idea to rig up something to make sure your speakers are covered in the event of disaster?