Thats why I use a line level component, with a tube, instead of tube amps. Tubes in line level gear offer the taste of tube flavor, but last a long time.
Amps in my application, long hours, hard use, tubes do not last. And vintage tubes are a finite source, and as many are now learning the joy of vintage tube sound, I see the source drying up even faster.
When it comes to 12AX7A,s Im partial to Amperex and RCA, both are absolutely amazing sounding. The tubes made now, well, I found them to be too much tube coloration, I used Sovtek, JJ, Ruby, and Electro Harmonix.
The old tubes sound natural, clean, and smooth, yet extremely dynamic, in that real sort of way only tubes do. Vocals through my vintage tubes have an acoustic sound, something I have grown very fond of, and Im getting this sound out of CD,s no less. Vinyl can sound absolutely incredible.
They always used to say that McIntosh stopped making tube amps when they did, because they couldnt get good tubes anymore. In my listening comparisons, the new tubes, well, they are tubes, but they dont really sound the way tubes sounded when tubes were really it! I like tubes from the 1960,s!
The right tubes are some powerful magic, at least I think so.