Here is a page that lists some of the differences in sound, between most of the Amperex 6DJ8 variants: (http://home.att.net/~chimeraone/6dj8sound.html) As mentioned by another poster; you'll never know what you like without doing the tube rolling yourself. The 50's to mid 60's Siemens CCa has been my 6DJ8 tube of choice for years now(my present CD player's output stage takes six of them).
Difference between Amperex 6922 pinched waist tube
I wonder if there are differences in the Amperex 6922 pinched waist gold pin tubes that I have heard about. I see some were made in Holland and some were made in the US. Is one supposed to be superior to the other. I have read that they are pretty much the holy grail of Amperex tubes. I just picked up some Siemens CCa tubes and really am impressed but figure I may as well see what else is in their league. Thanks for any advice as I could always use it.