If you had a dozen pairs of classic vintage ubes in your closet

Great question. But before giving you an answer, I'll need somebody to send me a dozen pairs of classic vintage tubes. I'll get back to you after that.

@testpilot

i do consider people may not be native english speakers, when appropriate... but not in this case though... thus my comment

@midareff1

have a little pride man... just look at your post title and initial post ... when i type something, i re-read it, make sure people understand and there are no glaring omissions or misspellings... caps aside...

or maybe lay off the booze when you are posting and asking for others' input here?

Elliott... you have a good point about the tube tester. There used to be one at a repair shop in Miami but he closed many years ago and I have not been able to find anyone with one. I use 6DJ8/6922 tubes. About 15 or so years ago I rolled everything I could get my hands on from all over the world. Bugle Boys/Amperex/Valvo/Chinese 6DJ8s/Telefunkens and many more. Discovered that the Siemens and Halske Cca 6922 Grey Plates round and D getters from the later 50’s and early 60’s were the best in my system, except for a stray set of 1958 Valvo Pinched Waist 6922 Cca tubes. Found a source in Germany and stocked up on the Siemens... they were about $40 each back then. Sold off a bunch at $200 each and still have a couple I just found in the back of the closet. I see someone trying to sell a matched pair @ $2000. Probably try the ones I have today. Currently I’m using 1975 6N23P SSW Russian Reflectors I get from a lady in the Ukraine and have watched them double and a half in the last few years. Have a couple of Russian Rockets in the closet too I didn’t like as much as the Reflectors.
Generally I’ll just run them until the bass or highs start to deteriorate and then replace them. I really like the tester idea.. want to keep my 30 year old pre-amp going as long as possible.   https://www.martindareff.com/Other/HDR-Treated-Images/i-ZmLg23s/A

A bell just went off Elliott....   we had numerous discussions on the dpreview website if I recall properly.

Are you talking about tubes as investments or tubes as electronic devices that are needed for music amplification?

As one who has been doing this for more than 45 years, I disagree that a tube tester is a requirement. Second, I especially disagree that a cheap tube tester is a requirement. If a tube has an internal short, you will know it immediately without testing it formally. You will throw that tube away. If the tube is wearing such that it affects sound quality, your ears will tell you that. If you have a voltmeter, you can test a tube in the chassis by measuring its associated voltages. A really good and therefore expensive tube tester is nice to own, because it gives you something to play with. However, even the common expensive tube testers cannot test a tube at the voltages and currents that usually exist in functioning equipment. Therefore, you would get a false impression of the performance of the tube in circuit. For most of us, it is best to just Use your ears. To acquire a tube tester that can actually test tubes under real world conditions will cost you well over $1000, more like $2000.