I am trying the Gold Lion KT66s in my PrimaLuna Dialogue Two today. Initial impression......they certainly don't sound any better than the Gold Lion KT88s they replaced. Might not have as good bass. Mid-range might be a bit more forward. Maybe a little rolled off on the highs. All that being said, in a blind test, I might not be able to tell the difference if the volume was matched. Definitely have to turn the volume knob up a tad higher as compared to the GL KT88s.
They are a better looking tube than the GL KT88 to me because of the bakelite looking base. Strangely (to me anyway), they are just as tall as the KT88s.
I've run Gold Lion KT77s, Russian 63PS-Es and NOS Siemens/RFT EL34s in the ST70 amp. The KT77s were a step up from the EL34s in fidelity to my ears. The 63PS-Es sounded every bit as good as the KT77s to me, maybe a little better. These new Tung-Sol 6L6Gs sound every bit as good as any of the tubes above and look beautiful to boot. I had no problem at all biasing them to the nominal 0.500 mV on this amp.
