The older tubes are better IF you have a reputable supplier that properly tests them. Some of the tubes are less microphonic, some just sound better because of the midrange bloom. This is a fine example of tweeks, but I have done this to my ARC gear with GREAT results. If you would like to know my tweeks, write me off line.
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?