6sn7 tubes for Atma Sphere amp

Does anyone know the respective 6sn7 tube cascode function relative to their positions for the MA-1 Mk 3.3 amps?

Congrats from me too...belated. The Atma amps are great and rise to the occasion. Some tweaking helps.
.Contrary to preconceptions that the input tubes are all that matter I changed all the output tubes to rca nos. 28 tubes in my ma1. Very good investment. While changing driver tubes has been so-so. But then i started from nos sylvania to begin with.

1Kitch, this may be obvious but Ralph knows anything you want to know about his amps. 
In terms of reviving the thread there isn't a great deal more to add than what was already known about tubes from earlier eras.  The RCA and later Sylvania tubes are still used and in reasonable supply.  6SN7s were made by the bazillion so decent old stock tubes are easy to find with a couple of exceptions.  The only 6SN7s I can think of that are new since 2010, are Psvanes and the Russian Tung Sol.  I don't know how either of them would work well in an Atma Sphere amp. Ask Ralph he might know.