Question about valves running hours


I'm new to the tubes world and when I bought my amplifier the seller told me not to run it for more than 8 hours, letting it for rest a couple hours before the next listening session. I wasn't told why, but now I got curious and I want to know more about it. 
What's the reason for this limitation? What can we damage and why?
128x128migueca

Showing 1 response by elevick

My work system is driven by a 55 year old Masterwork amp (by pilot).  I use it for 8 hour work days all of the time and it never fails me.  It does get hot but I make sure it's well ventilated.  If this amp can take the abuse without ever burning up tubes or caps, why can't a new one?