Telefunken Labeled ECC801S Made by Valvo

Anybody has experience with the above tube. What are the differences between the above tubes and blue print Valvo 6201
The Valvo blue pinch-waist 6201's are terrific sounding tubes (and very expensive these days!) The TFK 801s is also considered a premium tube, but regardless if made by Valvo or TFK, it is a 12AT7, whereas a 6201 is a slightly different tube (has a bit less gain than a regular 12AT7.) Many people consider the 6201 more refined sounding (smoother) than a 12AT7. A similar relationship as the 5751 to the 12AX7.

It's perfectly OK to substitute a 6201 for a 12AT7 in most applications. The slightly lower gain will not be an issue (except perhaps in a tube MC phono preamp.)