Inherent Difference - 12AU7 and a 12AT7

Some info on the gain characteristics of the "12" family of 9 pin miniature tubes:(http://thetubestore.com/gainfactor.html) I would suggest some of the better/quieter, and longer lasting, European varieties(NOS- Siemens, Teles, Valvo, Amperex, Mullard). I've listed them, in order, from most transparent, to warmer/tubier. YES- Each manufacturer has a characteristic sound, in MOST gain circuits, regardless of the actual iteration.

EAT DOES make the 12AX7 tube, but it is referred to by the European moniker: ECC803S, which was the best of the best, for that tube family(http://www.gcaudio.com/cgi-bin/store/showProduct.cgi?id=501). The 12AX7, and the 6DJ8/6922(ECC88), are the two most popular 12 volt, 9 pin miniatures(most commonly used), in the industry right now. I'm certain EAT took that into consideration, when deciding what to manufacture.