That is just one of those things that you have to hear for yourself and then decide. I experimented with various EF86 but I never did go hog wild and buy the truly expensive premium tubes so I can't say the 6BR7 is better or even equal to those tubes. When I compared the Brimar 6BR7 to various other EF86 in the same price range I liked them though I have to admit that the cheap pre-1970's Russian EF86 were also very, very good. But ultimately I switched my amp over permanently and am no longer using adapters because I like the tube. Sorry, that is all the help I can offer, I wouldn't want to tell you more than I think I know.