Why are older tubes so much sought after

Thank goodness Tvad provided such a perfect response, now I don't have to reply other than thank you.

I hope you guys have fun with this thread and convince yourself that NOS tube are not worthy of your system.

Good is what I say, all the more left for me.

I've returned my Aesthetix to the factory for upgrades three times in the last 11 years and every time they run the tests they are amazed at the results.

The difference between my Aesthetix and the ones they deliver new? Theirs are new stock Russian and mine is 100% USA, German and British NOS tubes, the best possible for each position in the unit.

Laugh all you want, but tubes are parts too. No one seems to think it's funny to use good quality caps, resistors and cables but cross over to tubes and the funny spring worm jumps out of the can.