"new old stock in white boxes" you should be wary. Especially if these NOS are not military (JAN) tubes. A box doesnt prove that the tube is NOS, but the lack of an original box usually is very telling.
I find this to be true, of all the tubes I have purchased the only one that failed was one that didn't have an original box.
I find this to be true, of all the tubes I have purchased the only one that failed was one that didn't have an original box.