@wmr57- my doppelgänger--you still using the Allnic phono pre? I rolled a bunch of rectifiers in that, finding the sweetspot for me, given my system voicing, to be the GEC U-52 cup base. I have a metal base Mullard (really a Philips-Miniwatt from Holland), a grail tube, but it had mucho bass and no "air" or nuance on top. For those unfamiliar with the unit, it is supplied with a cheap, crappy rectifier (or at least it was) and I suspect the manufacturer knew that folks were gonna roll it. It’s really the only tube that makes a difference in the unit.
@inna- with respect to Lamm, they supply a Sovtek 12ax7 as part of the full tube complement for the ML2 series SET amps when you buy from the company, which most do. Those usually get rolled by owners. I asked Lamm about it once- they didn’t really go to the trouble to source NOS 12ax7s (though a lot of the tubes in the amp aren’t new manufacture--you take your chances on the power tube/regulator Russian 6C33C which you can buy cheaply in the open market but there are risks of failure and those tubes have a weird range of bias that corresponds to each amps range for biasing them, a factor that Lamm keeps proprietary). The only tube I "roll" in the Lamms is the 12Ax7 and use an old stock ribbed Tele, which gives the amp a little more bite than the smooth plate. Both versions of the Tele sound far better than the Sovtek.
As to wide availability of common tubes, like the 12AX7, you can buy "pulls" of that tube all day that measure well. My experience is that they don’t last as long and go noisy. True NOS isn’t cheap if you can trust the vendor and my experience is that the amps hold bias better too. (Use a Fluke pretty much every time I run the amps to verify).
In a world where tubes were common and easy to get it was fun. Now that a lot of these are unobtanium--try finding NIB GEC KT66s as a quad (I did some years ago for my Quad II amps), it becomes another hurdle. I’m not in this for bragging rights, I’m in it for sound, which is why I suggested that modern tube amps that will sound good using readily available modern production makes even more sense today, with the depletion of stock.