Preamp Eats tubes..

Do you have a tube tester? Are you sure about how new your supply of 'NOS' tubes are? If you don't own a tube tester, maybe your NOS tubes are not as new as you think they are.

I haven't heard of the Sonic Frontiers Line 3 being a 'tube eater', but if you're sure your NOS tubes read good before you burn them up, maybe there is something wrong with your Line 3. Possibly bias or something is out of whack. Contact Chris Johnson of the Parts Connexion.

Unlike wine, I don't thing age improves tube performance or longevity.

Sounds to my like you need to get another tube supplier....

it's possible that the NOS have slightly different specs and aren't a good match for the SF circuit. my CAT pre is picky that way - it also likes the Sovteks better than some NOS I've tried.