I tend to agree with Thorman. I am currently using NOS Mullards (1969 xf2's)as drivers in my AES SE-811 amps. I tried the Sovtek and did not like them at all. I also tried the Tesla and Svetlanas. I thought the Svetlana was the smoother of the two. In fact, to my ears, the Svetlana is very close to sound of the Mullards. I'd try the Svetlanas first. Make sure you get a properly matched quad.
Premium Golden Aero Tesla EL-34
Im thinking about buying 4 for my stock DynacoST-70.I now have Sovtek EL-34n Will the Teslas destroy the Sovteks? What do the teslas sound like? Thanks!