Some of my favorite 6dj8 are the early 60s Mazda. I had a pair of these from Brent Jessee and they sounded incredible. Unfortunately they had kind of a short life in my CJ preamp. That thing was hard on tubes.
I replaced those with some mid 70s Reflektor 6922 . Another very good sounding tube and RUGGED. Those gave years of quiet operation whereas lesser modern tubes would sound good for a few months but get noisy. Like Audible Illusions the CJ preamps that used a 6922 ate tubes. The only modern 6922 tube that is consistently good in my experience is the Gold Lion 6922 gold pin , gold grid.
I like JJ tubes ,but their 6922 were hit or miss. When they were quiet they sounded great but in the CJ they weren't in there long before they were noisy
I use the JJ in my Quicksilver's driver tube and they are fine in that position
My Lab 12 DAC 1 Reference uses a pair of EH 6922 and after a year of use they still sound great . It sounds so good with the stock tubes I am actually afraid to make any changes. At some point I will replace them , most likely with Gold Lion .
The problem with 6dj8 and 6922 is that the NOS ones are scarce. I'm talking true NOS, not pulls that look and test new but genuine NOS
Once I bought a tube tester I quickly found out what tubes were good and what were junk. I discovered that most of the tubes I bought from trusted sources were as described. Strong emissions and balanced triode sections. Matched quads are matched, etc New production bought in a pinch from a music store were the worst. Readings were all over the map for 12ax7 and au7 type. They must get what everyone else passes on.