Most of the reputable tube dealers manually tested each NOS tube for low microphonics, low noise etc. Lucky people knows the difference between new and nos when it comes to the great tubes. I bet you have some decent NOS tubes yourself.Thanks!
Anyway it’s a good news that your or herron preamps works great with stock new tubes.
BTW i really like the design of Atma-Sphere MP-1 and MP-3
Actually I don’t stash NOS tubes and I don’t use them. My thinking is I should be able to make it work with the garden variety of what’s available. Further, we usually find that the tube dealers really don’t have tubes as quiet as the new ones (we have found this out when customers have sometimes ignored our advice and tried to use NOS tubes). So I really mean it when I say we don’t recommend NOS tubes in our phono sections.