Samhar - I'm not sure if my Amperex is the Holland or US version... if I where to guess, I think it's the US version but would have to unscrew the tube cage to confirm.
Since your recommendation on the Reflector 6H30P-DR tubes, I've done a little searching on the web, but they don't appear to be readily available... and supposedly, there some frauds out there. Besides, at $300 a tube and the risk of getting a fake, I think I'll pass.