You could possibly also try 5881 Tungsols or KT-66's. Check with your dealer.
Where to buy NOS 6L6 Tubes
Where is the best place to find 6L6 NOS RCA Black plate Output tubes for my Audio Research amp. I've heard that they are the best but I really don't know for sure. I'm using Svetlana 6L6 now and would like to upgrade.