Best 12AU7?

Telefunkin ,Siemens , all very good nos tubes from Germany 

I use 12au7 tubes in my DAC... have tried LaRadiotechnique, Brimar CV4003, RCA Clear Top, Telefunken amount others. These are my (4) favorites for sure but right now I have the La Radiotechniqe in and they seem play best with the particular speakers I'm using these days. These were never imported into the US so if you can grab a set, go for it. Not overly expensive either but really a spectacular presentation to to bottom. French tubes have a personality all their own. Just my opinion 

I can also vouch for Radiotechique. I am running the equivalent version produced for the French military, the 6189/12au7 in my Rogue ST100 and I would describe the sound as "Lush".

+1 on contacting Brent Jessee.

I have NOS RCA clear tops and black plates. The clear tops are brighter up top, but the black plates don't lack for treble extension and overall I prefer the balance of the black plates. Good luck with your search.

I asked for similar (not exact) recommendation from Brent Jesse and was recommended the Mazda Grey ladder ribbed. Been super happy with these.

Brent Jessee - 12AU7 in stock