[BrendaAnnD]

Yea, they are definitely an overseas type and from all that I have read, they are the same as our American types. They test the same on my testers, although I noted the 5Z4 did test stronger than a NOS 5Y3gt. The 6P3P tested like a 6L6GC. These appear to be all China made. I have had issues in the past with Chinese made tubes as far as life goes, but on the Russian made tubes - Zero problems. Here's a close up of the 6N8P tube, in which you can note that I am not using. I might later try a set of USA made 6L6GCs just to see if there be any difference in performance.

Have you had the opportunity to do a run up on specs? How much power do you get before clipping starts? What is your actual G2 volts (mine is giving me almost exactly the same as the plate)? Looking at it on a scope, it clips early (and badly) on negative peaks. It does get good power and sound before it clips, I just think it should be more symmetrical.