I have been an audiogon user for more than 10 years. I read audiogon forums often, but I never posted anything. Today I will make my first post.
Elrog 300B failure could be one of the two scenarios or both:
1. Elrog 300B has problem itself.
2. Some of Frankensteins 300B amplifiers if not all have design issues -- huge current surge when the power is turning on. As a result, tubes failed prematurely.
I used to own a pair of CST Frankensteins II 300B amplifiers. The stock tube failed within a month. Within a year, I had encountered 4 300B tube failures. I emailed the designer when I had my 2nd 300B failured. I was assured that the amplifier has no problem, I can use any 300B tubes for the amps, but the problem is I continued to encounter 300B tube failure. After a few month of search, I found a very reputable repairman in California. After he inspected the amps, he told me there was a design issue: huge current surge when the power is turning on. As a result, 300B tubes failed prematurely.