In nearly all my audio gear certain NOS tubes have been superior to those fitted by the manufacture. So many have not been making audiitoning a neccessity. If you develop a relationship with some of the NOS tube suppliers, most likely opportunity to experiment will be offered. Interestingly, in my CAT amps the Telefunken 802s, which were spectacular in my Jadis amp,have exhibited no improvement. Actually, a heavy, dark signature has emerged. Take caution with any investment and allow your ears to decide whether to replace or reject. Good luck. This can be a fun part of tweaking a system. The sound will efinitely change, especially if your system is revealing.
Why are NOS tubes considered superior?
The idea of "tube rolling" in my ARC preamp is something that I am considering. What I'm not sure I understand is the quality of tubes manufactured today vs. older tubes. It would seem that with modern manufacturing technology new tubes would be of higher quality than tubes made in the 60's and 70's. How are the older tubes better?