I had a similar issue many years ago with a Music Reference amp. Turned out to be one of the output transformers needed replacing. Not an easy or cheap repair.
Blowing Fuses. Dennis Had Inspire 300B SET
I was disappointed this evening, as I was listening and all of a sudden I blew a fuse, and I don’t have a manual. I don’t know if the fuse is a fast blowing fuse, or a slow blowing fuse. The one in there is a two amp, and the fuse itself is a zigzag not a straight fuse I replaced it. And it blew again and I saw the rectifier tube had a reaction when I turned it back on. Does anyone have any experience and can anyone give me some advice thank you.