Why are older tubes so much sought after

I am not sure that you can get good engineers to work on tubes these days. People are what make products good or bad. If you are an EE, will you choose tube design as your career?

They did not even teach tubes when I was in the EE program, and that was a long time ago....

Juanpablocuervo, Chadeffect, and Trelja,

What kind of music do you listen to? I have found with these more colored tubes, it sounds great with violin, guitar, and female vocal music. However, with piano and orchestra music, less colored tubes are more desirable.