Really fascinating information and a great read, but a bit depressing after buying at least two quad sets of the "new" Gold Lion KT88's. From this info, the lowest rated tube of all and we can get the same thing from Electro Harmonix for half the price. This new market for tubes complete with counterfeits and fakes and all kinds of chicanery is a drag. I did have trouble with a couple Gold Lion KT88's letting go never was sure if it started with the amp or the tube. What to do? Who's right? Even if you can afford the old original stuff you still don't know what you're getting the fakes are so very sophisticated and as the dude pointed out you may be getting a tube that is pretty much used up. In any case the guy sounds like he knows what he's talking about and has credibility. Is this also a problem with 6550's?