Audio hi-fi that "distorts" is very bad where-as guitar amps that distort is good.
A tube can test 100% good and still not have the mojo.
Not a fan of Jina or Slovak tubes. And the original NOS SED =C='s are all but gone and even those were just average.
No telling whats up with New Sensor Russia these days. Last quad Svets i got wouldn't bias properly and the vendor wouldn't let me return or get a refund.
And PP wouldn't give me my money back either and ive had a 20 yr history as 100% feedback. Try splaining tube bias complexities to the PP call center in da
Phillipines. Does not register.
Didn't have to do that twice. I went full NOS. Ive got a good stash and need not buy the junk floating around now.
NOS Mullard UK & Amperex Holland used radio-active isotopes and other chemicals long since banned thats why many 50/60 yrs later still have great complex midrange & test as new.
I'll stick with them.