KenRad CKR 6SN7GT tubes with Cary SLI-80 amp

Has anybody tried the black glass KenRad CKR 6SN7GT VT-231 tubes made for the US Navy with Cary SLI-80 integrated amp? They sound bright as compared to Sylvania VT-231 which have proved a very good match for Cary. Perhaps they need a thorough burn-in?

Thanks in advance,
I have done a ton of tube rolling in my SLI80 and by for the best combo I have come up with is as follows:
Late 60's Amperex 6dj8's Holland made A frames
1944 RCA VT-231's Grey glass
EI KT 90's Type II from Jim McShane
Mullard 5U4GB's

Bias the KT90's between 80 and 85
Sounds Awsome!!

Thanks a lot!

I will bear it in mind. Unfortunately, the only way for me to audition the tubes is to buy them.

Best regards,