Re: "Telefunken, Mullard, GE, RCA, Sylvania, Groove Tubes, Sovtek, JJ and countless other new and NOS (new, old stock) tube brands."
There is no such thing as NOS tubes. Telefunken, Mullard, GE, RCA and Sylvania have not made tubes in decades. The old stocks are all gone, and these companies absolutely do not produce "re-issues" of vacuum tubes either.
Everything sold under these names is fake: counterfeit labels put on JJ, Sovteks, Shuguang or whatever new tubes. Or worse: used, old tubes cosmetically refurbished to look like new. It's a scam to separate audiophools from their money, just like two hundred dollar power cords made from solid silver or directional audio cables.
Groove Tubes is not a tube manufacturer, but an OEM label. You're getting JJ's, Sovteks or whatever. Supposedly they provide value by selecting, grading, and (when applicable) matching tubes.
The only way you're going to get some genuine old brand-name tube is if by dumb luck you discover a cache of them in some forgotten cabinet in a run down building somewhere. Or pull a used one from a vintage piece of equipment.