NOS tubes

You'd figure that with social media and instant feedback today, that some tube maker would realize that making a superior product would kill the competition. That's assuming anyone gives a crap anymore.

I got a set of electro harmonix 7591 output tubes and 2 of the 4 went kaplooie in 2 months. I then sourced 4 nos Westinghouse and couldn’t believe how much better they were in their power delivery and Sonics. I only use telefunkens or Mullards for tone and phono stages. 
They sure were doing something differently back then if the equipment today is the same. 

Back during the golden years of tubed based electronics EVERYONE in the electronics industry and military was using this technology, do you think the tubes themselves were important? They were! And not all companies were equal. So yes and no is the answer to the OP's question. As is the case today there are some tubes being made that are STELLAR but most are pedestrian at best.

Matt M

I don’t think that’s true freediver. Current production tubes are made in Russia and China and their construction is very different from the classic tubes made in the US, the UK, Holland, West Germany and many other countries. I’m not saying that they don’t make good tubes today, but they’re not made on the same equipment that the classics were.

There are cases of countries buying tube manufacturing equipment and using it after the original companies shut down in the 1970s. Ei in Yugoslavia bought Telefunken’s old equipment and someone in Japan ( Mitsui maybe?) bought some of Mullard’s old equipment and continued making tubes.

Some people prefer current production, I prefer the classics for the reason hifiman5 stated. Different brands have their own sound characteristics which can be used, along with other accessories, like cables, to tune the sound of your system. It’s just my preference. Some people don’t like to use tubes at all. They prefer SS.

To answer the OP's question.  And I'm talking about preamp tubes not power tubes.  Tube quality was very important back before transistors replaced tubes,  when tubes were used in essential functions in airplanes, radar, early computers, television broadcasting, medical equipment, etc.

They are getting better at making tubes but the really good ones often cost as much as NOS.  You would think that eventually they will make tubes that sound better than NOS with the technology available today, and I think they probably will, but for now I prefer old stock to the new production tubes I've had in my system.