As good as it gets


I recently purchased a new  integrated amp. It has tube's and I wondered if there is a burn in period, or do they sound as good day one as after 4 weeks?
mfdamon
Always a burn in period of perhaps 50 hours and of course tubes need 45 minutes to reach optimal thermal efficiency to stabilize and sound their best.
Of course it will sound better. And not just for 4 weeks either I bet. 

Tubes are the least of what benefits from being used. Most of the sound of a tube amp is transformers, followed by caps and then circuit design and parts quality. Very little of it is the tubes themselves. But tubes are the one thing guys feel comfortable changing. So being guys they assume what they do matters. It must be the tubes.

Its not the tubes.
new tube amp needs to run for at least 50 hours music or no music, as per @celtic66 , but bare in mind, it's best to turn off tube gear when not under control for safety.