Andy is slow, but good. Brent does qualify what he lists, but does have true NOS- which he will usually call out, but check with him. I prefer phone to email although as a retired lawyer, having things in writing is my first instinct. The trick is to work with these guys, particularly Andy, and go with it. That works better by phone since I don’t think Andy even does email.
It also depends on the tube, obviously. One thing I found-- in my Lamm ML2, I only roll one tube, a 12ax7, a very common audio tube. (The rest come from Vlad directly).
When checking bias, any so-called NOS 12ax7 Tele ribbed plate will eventually lead to constant adjustments- for some reason, putting a fresh, old, never used Tele ribbed plate = extremely stable bias (using the requisite Fluke meter). Trying to find those relatively common tubes (I paid 10 bucks a piece for them back in the ’80s as old stock) isn’t easy. And, Andy won’t sell Russian tubes, e.g DR variant of 6H30, another really hard to find tube as true old stock that hasn’t been counterfeited.
I’m a dilettante when it comes to tubes, though I’ve been using them exclusively in my hi-fi systems since the early ’70s. I do not profess guru status. There’s a lot to know. I bought some Mullard tubes for my Allnic H3000 a number of years ago, branded on the glass as made in Great Britain. Turned out they were made in the U.S. by Amperex. At the time, tube companies shared production capacity to meet demand when tubes were mainstream-- it wasn’t considered deceptive. But, given the prices now commanded for vintage tubes, you either work with a trusted dealer, take your chances, or find a current production tube that works. I gather, from discussions on the 6H30, that the current production Sovtek/EH is fine for some equipment but can hear the difference between the new production and the old DR variant on my line stage. So, some of it is circuit. There are also so called Kardashian tubes which are famous for being famous. Would you pay 19k US for a pair of real WE 300B? Some might, and not blink.
Bill Hart