How come that NOS is better them NS new stock ?

One thing to keep in mind regarding NOS tubes. Most of what we call NOS tubes were made at a time when many countries were at war.The periods of the 40's and 50's saw production of German Siemens, Telefunkens etc.. as well as American tubes used in military applications for the Army and Navy. We see many of these tubes today as JAN labeled, HM for Hungarian Military in the case of Tungsrams, and other applications such as medical equipment Amperex(although much later 0n ..i.e. late 50's) found uses in domestic and foreign products where reliability was necessary for product sales..TV's radio's etc.. The fact that many NOS tubes were commissioned by Military forces to design a quiet, dead reliable,and long lasting valve for use in military radios, transmitters, and even jet aircraft. Many of the older Russian Mig jets used tubes in their radios in flight. Over the later years and as the political climates have changed, along with the proliferation of SS designs,many once thriving tube manufacturing plants were not able to keep quality control in their production of their tubes. The Russian Sovtek plant is a good example, and now has been bought by the American company New Sensor..who is now making fabulous tubes once again under the EH brand. Just FWIW..Enjoy the TUBES!!