My impression of the 6A3's is changing as probably the tubes are with some burnin use. They are late of late '40's vintage and as me, they may have been a little gassey; nothing that the getter couldn't burn off
Nevertheless, their producing the most holographic soundstage that I've ever heard. Separation is pretty amazing. Whether they will ultimately be my primary tubes, I haven't a clue. But, they are sure fun to listen to. Not bad for around $50 a piece!
In the meantime, I post my thoughts when the 422A arrives....