How do you test different tubes?

Byans I'm afraid that's the price of admission and knowledge. Learn a little spend a little

And then also you are usually buying those tubes someone else 'did not like'
So the unwanted tubes just keep going round and round...
Good tubes wind up in 'collections'

IMO the problem is all the good tubes are ALREADY in someones stash, and have been for years.
My recommendation is buy new tubes, not NOS or used ones.

PS I do own a tube preamp, but i really have little interest in tubes for the reasons i mentioned.
Maybe i am wrong.. but I do not think so.

Elizabeth is right.

NOS tubes in any quantity are all gone, used, and burned out, and have been since the 80's.

Only the Russians and Chinese have made tubes in any quantity since then.

The Russian tube factories are controlled by the Russian mobs, and tube types come and go. The Chinese tube quality is very "spotty".

Try and find what is the best of new tubes, and buy a lifetime supply!

One thing that is nice about tubes is that they can be very easily tested for quality control. Because of that used tubes are a very viable option. The market in used tubes is virtually unlimited.

Also, in my experience the price of tubes is distorted by collectors/hoarders. Certain tubes and brands are commanding very high prices when there are readily available alternatives at much lower costs. For example, Mullard or Telefunken 12ax7s compared to U.S. made "organ" grade equivalents.

One last point, the differences between high quality, properly functioning tubes is subtle, yet like most things audiophile related users describe the differences as huge and earth shattering.