Mulveling, good points on the 6SN7’s.
Audiojan, reason why I think it’s important for one to hear the tube in ones own system is because what sounds good in someone else system may not sound best in yours and you might have a different preference. Example, many people like the 1940’s Metal base Sylvania 6SN7GT or 6SN7W. I really don’t, I prefer the Sylvania 1945 6SN7W short bottle because I find it sweeter and nicer than the more expensive and sought after metal base (taller bottle) which I find a little too analytical for my taste. The 1945 Sylvania 6SN7W short bottle and the 1951-53 Sylvania 6SN7GT Chrome Domes are probably my favorites from those type tubes. Mulveling, you mentioned Shuguang and JJ Czech in your post. Because I use so many EL34’s, I’m using 8 Shuguang in my CJ Premier Four and in my CJ Premier 1b, using 12 JJ from Slovakia Czech. My VTL all have 16 Russian EL34’s.
Inna, I never thought the Svetlana/SED EL34 "Winged" were anything special. And even though people claim they are a close copy of Mullards, they’re not. Not even close. I’ve found a few EL34’s that nicely outperform the Svetlana tube. One of my personal favorite EL34’s are the 1970 Tesla brown base. Very revealing and beautiful sounding tube. I like it in some ways better than my Mullards. The Svetlana winged C doesn’t compete with these caliber of EL34’s even though people have falsely claimed so. I mention in a previous post, I would only use inferior tubes in my equipment because it might be too expensive to use premium tubes. On my amps that ONLY require 4 EL34’s, I have on most of the 1970 Teslas, 1960 Mullards or 1960 Amperex XF2.