@nightfall And yes, the quad of 6SN7's that the Cary SLP-98 uses concerns me a bit because of what a costs for a nice quad of those NOS tubes.
I have a set of very nice 4+2 [quad plus two spares] of 1960s Sylvania 6SN7GT Black Plates stored away - no longer in use. No need. They were originally NOS, now low use vintage. Guess what, my current re-issues from TJ Full Music and PSVANE Art Series MKII beat them sonically to my preference. The vintage have detail just not the smoothness and texture I hear from tubes I can buy new now. Imo, the older vintage tubes are old and getting to be long in the tooth now. They are my backups.The question on the new tubes is how long they'll last. So far so good on mine.
I have notes on what Dan used in the Modwrights Preamps shipped out stock 5-7 years ago. I use the same OEM tubes rebranded from same provider, originally.