@kba_8040 - I don't have the Leben, but to ghasley's comments about different tubes and their sonic signatures I provided below the link to BrentJessee's website - a tube seller. You can look up the specific tube type e.g. 12au7 and aside from listing what tubes he has in stock he gives his listening impressions on the various brands as well as the respective variants for instance 12au7 - 5814 - ECC82 - 7316. Perhaps a look will be helpful to you.
Tube Rolling Leben CS-600X
I acquired a previously owned Leben CS-600X a couple of years ago and have really come to enjoy its sound. It's my first tube amplifier, I'm interested in exploring what more the Leben has to offer by replacing the tubes, and welcome the experiences/recommendations of others. The amp is currently running:
1 Sylvania 6DN3
4 Electo-Harmonix EL34EH
Interestingly, amp is currently running a JJ ECC802-S in both 12AU7 sockets and one of the 12BH78 socket. The remaining 12BH78 has a JAN-6189W
This article was interesting (https://jeffsplace.positive-feedback.com/tube-rolling-in-the-new-leben-cs-600x-integrated-amplifier-sophia-electric-vacuum-tubes-nos-12bh7as/) but I am not sure I want to invest in Sophia tubes when the cover will not fit back on the amp.
Feedback/recommendations on tubes welcome!