I stumbled on to this old thread. Years ago, I got hold of someone's recommended 6SN7 tubes, and I got sort of a pair of each, must have been about a dozen, RCA, TungSol, Sylvania, CBS Hytrons.... regulars as well as the military VT231's. Someone here highly recommended the RCA. I suspect it's the RCA VT231's also... is that the right name? Anyhow, I agree it's a good tube. Somehow, somehow.... oh, I built a preamp from the demised AES company. Then, a CA friend added a rectifier for me..... With all the 6SN7s I've used, I just love the Shuguang 6SN7s. I personally love it for its tonality. For example, the RCAs are good/great, but the Shuguang's mids are just lovely, lovely. I liked it so much that one time in China, I bought a dozen pairs, at about $10 a pair. I was actually in the town where the maker is/was, but I never visited the company, sighhhh!???? The Shuguangs have fantastic mids, where the money is, tho in my system it's a bit not as dynamic as the RCAs..... But... I love to live with the wonderal tonality of it.
I saw some familiar names posting here, so I thought I'd pitch in. I'm not so much into audio anymore even..... but, here and there I'll play my system, with all its flaws.