Good sounding 12AT7 for Nagra PL-P

I just bought a Mullard NOS 12AT7 from Upscale.   Kevin's reserve.   You pay a little more but I have purchased a few of uncle Kevin's stash and they were high quality.  I got some really good 6n23eh from upscale a while back and they tested strong and sounded great. 

Please confirm you installed them in a Nagra PL-P.  Thanks.

No Nagra here but the best sounding 12AT7 that made my amp sing like no other is the rare Brimar 6060 Yellow T tubes.  Quiet, detailed, dynamic and just filled the room with realism.  

I don't think 12AT7s are typically known for being a musical tube. Usually used in a phase inverter position most important is getting a strong testing balanced tube.

I often use JAN 12AT7s in guitar amps. Very reliable.

12AT7 are common on guitar amp reverb tanks , I have purchased at7s from a guitar shop in a pinch and they were poor quality...  Im guessing they are other people's rejects.  

Agree that JAN tubes are probably the best choice.  Unlike many other tube types like 12ax7 and 12au7 ,  nos 12at7  are still plentiful and reasonable