I am only 26 years of age, and am fairly new in the hobby, and am still learning. So , I called Bryston a few times, talking to them is fantastic. They talk to you like a human, and give it to you straight up, in a polite manner. There is, I believe a 75 bench fee and then they call to you let you know what is wrong with it. I can almost guarantee that it will be much cheaper to fix the 4b then to buy a new amp. But hey, its your money, I don't want to spend it for you.lol. The original 4b's NRB/Legacy series are not upgradable to the SST. Even if I were to go buy a new SST amp, personally, I would probably still fix the 4b. You just can't have a broken 4B laying around. Cheers.