Good Tube Selection for Atma Sphere S30?

I'm putting my Sylvanias back in:)

Thanks, Ralph. Excellent info.

What prompted my question is that I am using a matched quad of a highly regarded and expensive current manufacture 6SN7, of Chinese (not Russian) origin, which in some sections of some of the tubes measure as low as 3 or 4 megohms. I won't mention the name, but it is reminiscent of a famous Italian actress :-)

That results in a very slight hum with my VAC amp and 97db speakers. The tubes sound wonderful otherwise, btw. Some vintage CBS tubes I have, which sound poor in comparison, have no measurable leakage and do not produce any hum.

Thanks again. Best regards,
-- Al

If I'm guessing the correct manufacturer it's too bad the curves of the glass envelope of those tubes aren't more reminiscent of the famous Italian actress. They'd be a lot sexier.