GE 6L6GC bs RCA

One other strong performer is the Tungsol KT66. It draws filament power in accordance with 6L6 spec, has the heavy KT66 glass and gives a great sound: mellow, articulated bass and sweet treble.

for what application??

used as driver tubes on Wavac Ec300b in front of EAT and Takatsuki 300b. The KT66 works best with EAT, the Sylvania Winged-C best with the latter

Its surprising to hear your collective comments on some of the Tung Sol re-issues and the Genelax.  Makes me wonder if the NOS craze is all hype.

Not all hype - but new tubes are better than they were.