When PS Audio began in the early 1970s, Stan and I would not allow power switches on our products. Nada. Nothing.
Why? Because neither of us would tolerate the idea of turning products off, only to then force owners to warm it back up again before listening.
So counter to convention was this practice that several owners cut our power cords and added their own switch.
We would not be deterred. Our products were going to stay on 24/7. There were a couple of reasons for this. First, solid state electronics has a longer life cycle if left on. Constant power cycling stresses components, shortening their life. Second, we knew back then of burn in and warm up time. Left on for weeks and months at a time, our products had a distinct sonic advantage others did not enjoy.
Over time we learned to compromise. A little. Our front panel "power" switch turned off the indicator LED and muted the outputs—effectively rendering the unit off without compromising our values.
Which is why the vast majority of our products still run warm even when "off".