Most Musical 6NS7 tube for a Preamp?

I love my Audio Note linestage. It’s a M2 Special, which I’m told was a custom order from the factory.
A used M2 would cost $3000 or less. Audio Note products are built to last a lifetime with regular maintenance and upgrades. Mine is 15 years old and sounds wonderful. It’s dynamic with a wide, deep soundstage, and presents a transparent sense of realism. Not tubey, not clinical.
6SN7GT gain stage with tube rectification and regulation.

I've owned the Don Sachs model 2 and DeHavilland Ultraverve III and compared side-by-side. I sold the Don Sachs. 

I only know of one company who only make a line stage and line stage with phono and have been perfecting it for decades: Audible Illusions. A preamp company. And the only preamp that has consistency received TAS Editor’s Choice award saying “one of the best at any price”. A SET design using only one tube per channel, it is uniquely transparent and musical with no particular sound of its own. Separate power supply. A used L3A that is fully factory refurbished with new tubes and upgrades can be found used for around $2500. Used is preferred for 95% of new that is now $5200.
But to be compared to an $80k preamp is not only valid but justified.
Not that I have owned such a preamp but I have owned a $20k Rowland and a DeHaviland and others and would new never own other than an AI.

Recently purchased a Supratek Chardonnay and told Mick just put in the best of everything, about $3500. KenRads, Psvane, GE, Sylvanias, Bad Boys and Chrome Domes, Shuguang, and a couple of others. Psvane CV181 TII won the day. Best bass combined with balanced musically. How do I know? I now need a rumble filter. Best bass I've ever had. 
And BTW, I absolutely love the preamp, it replaced a much more expensive unit.

KenRad VT231 black glass....Sylvania 6SN7W....my two all time favorites