There are a few tubes that are recommended time after time in this thread. Some are afailable from sellers in remote countries. How much do we need to worry about fakes? thanks
see brent jessee’s page re 6dj8 fake telefunkens with chinese counterfeit silkscreening, informative... bottom line if you know these tubes, key indicators of their construction that identifies them, really convincing fakes won’t get by a cursory look by an experienced tube guy
what IS the worry is used tubes, with lots of hours, severe imbalance across the internal dual triodes, and noise/microphonics... let’s face it, these tubes are no longer made for 20-30-40 years now, folks test 'em, use em, pick the good quiet balanced ones and leave em in to make music, set aside the noisy crappy ones, so what remains available today are more of the poor ones that fail on one or more of the above attributes ... unless they are coming out of a reputable seller that tests on all these key parameters or from an old hand who has had gems stashed away for half a lifetime...