When I recommend tubes, I always enclose a caveat about not spending a ton of money on tubes for this amp. I have never recommended someone go out and spend even $45 for one of those gold lion reissue tubes. I'm not even sure I'd call anything made today a reissue, since they aren't made by the same company - or even in the same country. To my knowledge, its now the same Russian company that makes the "reissue" Tung-Sol tubes. Bleh. That is not to say I haven't spent way too much on vintage tubes. In my defense, I'm also going to be using them in a Bottlehead Crack, when I finally get the time to build one. I have a couple of vintage GE 5-star 5963 tubes with red labels that sound quite good (I think I paid $12 for the pair). I think I have an RCA long black plate 12AU7 somewhere, that also sounds quite good. I can't say that any of the other GE or RCA tubes I've heard were outstanding, other than to say that any of them are better than the stock Chinese tube. I have a few Sylvania tubes (some that are rebrands) that are also unremarkable. But when you can pick them up for $2 or $3 each in a small lot of tubes, they are interesting to compare to other tubes. What I personally would do (and sometimes still do just for fun) is look for a small lot of say, 5-10 tubes of different types, and put in a low bid on them. Say, $10-12 bucks. If I don't win, no problem. Someone else wanted them more than I did. But sometimes I will win a small lot in that way, and I'll get a nice little selection of tubes to try, for not much more than it would cost me to buy one brand new Russian tube. People should keep in mind that there are several variants to the 12AU7's that will plug right in with no changes (5963, 5814, 6189), and those variants are often dirt cheap (because people insist on 12AU7s). I have even picked up an old Mullard using that technique (it probably was unbalanced or tested quite low, but who cares with an amp like this). It does help to know the value of what you're looking for. That takes time, and sifting through lots of auctions. I find it just a whole lot of fun, but it's not for everyone.