Great read, thanks for the post. Now I fully understand the reliability issues with the earlier Elrogs, was always interested in purchasing, too many reported failures kept me away.
Coincidentally, I was also running AR SP9 back in same time frame, went to Joule Electra LA100 MKIII which blew away the AR. I also was into 845 tube, used 845 amps exclusively for perhaps fifteen years, and then I find the 300B!
Lots of nice 300B's these days, good to see Elrog's continuing research with this tube.
