I have a Phase Linear amp that is almost 30 years old, and it is still cranking. I am going to have it worked on though, as I was advised that some of the internal parts need replacing from time to time. When I get it back, I will put it into a vintage system, that I just recently started using again. All of the other pieces I bought in the 70's, as well. It all still sounds great!
Sonny
Sonny