@couger4u I’ve tried various 6SN7s in my Cary tube preamplifier. Reliability has been better buying from reputable distributors who actually re-test them well before sending them out. People here all have their favorite dealers, re-sellers.
Not wanting to deal with boutique dealers as much for my backup sets I’ve had reasonable luck dealing with Viva Tubes, both input and output tubes. Sure, I also purchase NOS stuff from the speciality dealers too, but don’t use my vintage tubes as much any more. Hoarded a few sets away, but wanted to find new re/production 6SN7 tubes to use instead. I don't feel as bad running them more often perhaps.
Having tried TJ Full Music (n/a now days, but I still use them today), then tried special production PSVANE, vintage Sylvania, RCA, repro Tung Sol, and more, comparing with friends, some have moved on to Linlai too, with decent results. Some buddies are telling me they like the lower level model PSVANE and the lower model Linlai as much or better in some ways, slightly less smoothed over, fwiw.
VIVA: You might call Viva Tubes and ask them about their guarantee, returns, and ask how they will support you since 6SN7s are expensive, worth doing some added Q&A with them, comparing to other retailers. I feel the support and guarantee is as important as the tube itself.