tube amp - cool down

Does anyone know why the amp should fully cool down? Does it have something to do with discharging capacitors?

I would think that full cooldown is undesirable. If a tube is still warm when it is refired, the thermal stress to the tube filament would be reduced. Also, the warmer the filament, the greater the resistance, which would also slow the in-rush current, and again, result in a gentler restart.

Any technical guys have a reason for this advice?

Hi Jsman,

How is turning an amp back on before it is fully cooled down hard on the rectifier? If anything, a completely cold start is harder on the rectifier because the cold filament means low resistance (so, high in-rush current) and very rapid heating and thermal stress.