Just a short post regarding the sound of different EL84's I tried:
Chinese Shuguang 
To my surprise, these are very good, very tough and the cheapest!
They do need a few hours burning in. About 20hrs would do. Their sound is very good all round, no specific strengths or drawbacks, just sweet. Once I had a mishap in my biasing, and the plates glowed red for about 30 seconds before I noticed it, it did not damage, and the sound was same after it cooled.
Ei Gold (with gold Pins!) 
Rubbish! and the most expensive!
Sounded nasal, closed in. They were a matched quad ( I verified them), but I could not tolerate the sound. gave them every chance, but eventually I sold them on ebay for good money (they had gold pins after all). The buyer left me a positive feedback, saying they sound awesome in his amp, Well . . .
Russian (Reflector?) 
Perfectly good, with more bass than the Chinese.
Sounded punchy and clean, and the second cheapest! you can buy them at very reasonable prices, I could live with them, they do not drift either.
Sovtek EL84M 
I suppose they are good too, but nothing special to justify the extra cost over the cheaper Russians. Infact they are the same. You just pay a little extra for the M on the print, but they are no better sounding.
NOS RFT 
Clearly the best of the bunch.
Bass is not as powerful as the the Russians, but it is better defined, midrange is clean, specially vocals. The top treble is a little softer, so it does not have the sparkle ( or ear-ache) of the others, but cymbals and bells are clear as a bell!
I am also getting a set of Triotron (Philips) soon, I'll let you know soon as I know.
