I have always liked tubed pre's. Keep in mind when hunting for 12AU7 tubes that there are many designation numbers for the same tube. ECC82 is a European designation that includes Amperex, Mullard, Telefunken. Mullard and Amperex also made a CV491 longplate tube for the military, These things are "oh boy" if you can find them. 7316 by Amperex is another incredible tube. Then there are 6189 or E82CC. Also look for E80CC, ECC802, 7730, and 6680. They will all work as would a 12AU7. In my opinion there is not a currently manufactured tube that can stand with the NOS both for longevity and sound. I wouldn't give you much for any of the Chinese tubes. And the Russians arent much better, even in the NOS range. KEEP IN MIND THIS IS JUST IMHO. AlTran apparently doesnt care for Telefunken. I love them. And depending on if you are looking for cooler or warmer, NOS Amperex, Mullard, Siemens, Philips, and Brimar are very nice. Keep in mind that many NOS American tubes are European made but branded as RCA, Sylvania, GE, and Raytheon. Some of my favorite tubes in the 6922 and 12AU7 series are Siemens / Halske made Raytheons. Anyway, my Uncle was in the TV and radio business some time ago and had good batches of some great tubes that were just kept, never thinking that they would ever progress past their $2 to $10 former price range. I was fortunate enough to work with him when I was a young-un and learned a bit about the electronics building business although I never stayed with it much except as a hobby. But I do have a pretty good knowledge of tube origin and sound. But just be ready to pay thru the nose on some of the more rare NOS, as some of the dealers are marking thiese things up by the month. But know that in most cases you will get 3 to 5 times the life out of NOS. And when these things are gone, thats it. Nobody is making them like they used to. Maybe I'll get my hands on a Candela and do some tube rolling, but when my all in Odyssey monos arrive I'm gonna play with a very exciting Musical Paradise MP D2 DAC / Pre that is a tube and cap rollers dream (or nightmare depending on how you look at it.)