I have found and mfg state 100 hours to fully runin . The new metals need to season or settle in as in any metals they sound a bit bright the first 50 hours or so. Power tubes get hotter faster
and tend to settle down quicker. Some specialty brands say 200 hours I think 100 hours is pretty safe bet.
and tend to settle down quicker. Some specialty brands say 200 hours I think 100 hours is pretty safe bet.