unless you're going to pay up for vintage UK gold lions, don't gamble your money. I tried to find a decent quartet of gold lion KT77's for an amp and everybody I talked to said they had had nothing but trouble with the new production gold lions- TC tubes stopped carrying them because of it, they're not the only ones. That was a couple years ago- but I half-heartedly tried to get a pair of GL KT66's for my superdrive 45 recently, and everybody said the same thing. Dunno if anybody else has had good luck with them though- but I wouldn't bet on it.