Audio Research SP-10 6922 or 6DJ8

Thank you Albertporter for confirming my suspicion that the"naturalness" was in fact due to tube wear. All other tubes in my unit were not replaced.Has anyone been able to replicate the great sound of these NOS tubes. We read how the Chinese and Soviets have "EQUALLED" the sound, but it may be a case just like the Stradiarious violin. What do you think?

The topic of tubes has been covered here many times, but to answer your question, the Russians have done a great job on some tube types and not well at all on others. Unfortunately, the tube you and I are discussing ( 6922 / 6DJ8 / 7308 ), has not seen quality manufacturing by anyone that can equal the best of the new old stock. There is a huge demand for this tube type, and the need grows every year. Perhaps a US importer or distributor will invest the money needed to get a break through in quality on this particular type. I suspect the Russians are currently building the best tube they can, given the budget, tools and materials they have to work with.

Any thoughts on tube selection (6922,6dj8, ecc88) for ARC SP9 mkII?