OT question about replacing power tubes in ENGL Fireball

[MarkIVwidebody]

If I replace the tubes with a matched quad, do I need a bias? I was told that it would be safe to just switch them out if they were matched. They are different brands.

 

[Nermel]

If I replace the tubes with a matched quad, do I need a bias? I was told that it would be safe to just switch them out if they were matched. They are different brands.

Shouldn't matter...just as long as they match in pairs...and since all of them are matched...they should

 

[MarkIVwidebody]

I want to put in all 4 Mesa 6L6's.