I stopped logging in hours at 150. I think I have 200 hours on the GL 12au7s. It is noticeably quieter than the telefunkens. Regarding your comment above, I lost the details and bass because of the speaker, not the amp. When I switched back to the Cornwall IV, I heard the beautiful highs and bass again. I just need to stay below 90 to 95 db to enjoy it without being harsh. So sometimes it's not just the amp, it could be the speakers or the room itself. I would suggest the OP to try out a less sensitive speaker to confirm if it's really the Primaluna that's bright in his system.