Simple question, probably stupid

The point we are trying to make is—burn them in by enjoying them.  They should not sound horrible in the process.  It will also add to your knowledge if you listen to the process instead of just using the tubes as room heaters.  

With new tubes from China, Russia 50 hours is pretty close to runin 

and not anywhere close to NOS tubes which take 2 x to settle in any last much longer the tube standards were far better ,such as 98+ % vacuum 

vs 92-94% today , the metal recipe quality is not there back in the 50-60s grids many times inspected every 100 pcs now many every 3000.

the new Gold lions they bough5 the name ,not even close to the originals.

Tungsol made the Best 6550- today called kt88, even GE  much better 

or Japanese made from the 70s. That’s why I only buy or have custom built 

by RaduTarta  SET or transformer ,choke coupled preamplifier ,for quality throughout no China or Russian Anything. Emission labs makes nice tubes 

as well as Western Electric 300B orTaks from Japan.

I suspect they’ll sound great fresh out of the box…with potential to improve even further from there with time.

Admittedly I’m a bit of a burn-in skeptic anyway. It’s a very convenient way to minimize returns. I won’t mention the brand but was told a firmware update requires 300 hours of burn in.

I listen to tubes I roll as they burn in, and here's what I've noticed in my system: Power tubes and rectifiers 25 to 50 hours, signal tubes 50 or more....all of my signal tubes are mostly 50s and 60s NOS. They all sound good out of the box, but I won't listen critically until about 50 hours

Hello mazian.  It is important not to operate a tube amp using output transformers without a load on the output terminals. (As opposed to solid state amps which don't care about having speakers connected.) The advice of others responding before me is quite useful. So if you decide to play music while putting hours on the tubes (not really necessary, as they won't sound "bad") substitute a suitable resistor for the speakers if you don't wish to hear whatever is playing.  I encourage to play your favorite tunes and enjoy the music.