After many years (20+) trying different tubes my go-to now is JJ from tubestore.com Not because they are the absolute best - although they are better than most I've tried that's just me in my Melody. But I have never had a problem with any JJ tube. Maybe I'm just getting old or jaded or something but with so many other things out there that can make a much bigger difference with nowhere near the risk of headaches of tube rolling I go with the tried and true JJ.
BUT, if I really did want to try something different the man I would call is Dave Thompson at Raven Audio. https://www.ravenaudio.com/
BUT, if I really did want to try something different the man I would call is Dave Thompson at Raven Audio. https://www.ravenaudio.com/