To my practice, solid state amplifiers need more warming up time than tube ones. I have two of them, one push-pull with 12 tubes and the other SET with four tubes. In a few minutes they sound good, while my class D solid state amplifiers need a few hours to get closer to the best.
Does anybody know if tube amplifiers with speakers hooked up but without any signal can stay powered on without harming them? Many years ago I got to know a very nice guy from Boston area. He was then a Thiel dealer, in particular. I was excited then with new Thiel CS 3.7s. I lost a contact with the guy, but this is what he told me.