Question to 6L6 tube experts


Who can tell me whether the NOS TungSol 6L6 WGB tubes are suitable replacements for Sovtek 5881/6L6 WGC tubes? I am a complete nube in 6L6 variety and I am afraid of making a mistake!
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Jedinite24, as per articles by Jeff Day and others I would contact Jim McShane, inquire about the NOS 6L6 Russian tube 6N3C-E also known as a 6P3S-E, cost is around $65.00 per quad, very reliable and sound great! I have a quad in my Primaluna Dialogue 1 and they completely transformed that unit. Read Jeff Day Blog, he has them in his Leben amps. Jeff wrote on them at 6 Moons.
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I didn't think KT66 tubes were an exact replacement for 6L6GB tubes. Thanks for the lead Mcgarick. I'll have to do more research.