I would contact Chris Johnson at parts connection regarding your pre (he built it) I have used Amprex bugle boys and orange globe with no problem and long life with a line 3 before.
Preamp Eats tubes..
I own a sonic Frontiers line-3 preamp.The unit eats up NOS tubes.I tried Brimare and matsushita's both within 2 or 3 months the tubes started going microphonic on me.I put in the origanal Sovtek tubes and they work fine.Why does this happen with older style tubes?Are the sovtek tubes built for a tougher demand?