If I may, I will add a few more thoughts to my previous remarks.
Jafox..thanks for the support...your credentials and experience are well known to those who regularly participate here on AG.
I have no desire to flame any particular tube, because I have seen too many variations, and believe that in some piece of gear whatever tube we talk about may be very good. With that said, and having used a DAC that is very sensitive to 12AU7 selection, in my experience, the Telefunken ECC82 is no more than middle of the road....better than some, but very much exceeded by others.
In my experience, the pinnacle of the 12AU7 family is the Siemens Silver Plate ECC82....it leaves everything else in the dust.
Rediculus, if you wish more information, email me off-line. I can send you a copy of my notes on the family and share some of my observations if you wish.