What's the best 6NS7 tube you have tried in your Atma-Sphere MP-3 preamp?

@marco1

No, the cv181z were always real stable. That being said, the tube pins and socket connections are sensitve - you just couldn't push a tube in and let it roll. Sometime it's needed a VERY MINOR tweek of the tube - adding a little twist, little bit of lean, or just a reseat is all it would bring it in  Don't discount the signal tubes either

No sweat, @marco1 , I didn't take anything negative from it, I was just replying in a neutral tone.  But thanks for following up.  

Based upon Don Sach’s recommendation quoted by Whitestix above, I got Ray Reserve 6SN7s for my Valhalla integrated and immediately noticed more detail without any sharpness or glare or the expense of the lushness of tubes. These tubes are expensive and liable to get more expensive if tariffs come to be. There are Ray Select tubes that are about half or less than the Reserve but I haven’t heard them. I found them to be better than the Linlai tubes I had in place.