Why No Power Button on Some Phono Stages?

I turn my doorbell off when I leave the house. It doesn't seem to have any effect on the sound.

"While I do agree that it's optimal to listen to components when they are at operating temperature, I would like the option of turning off a device easily when I choose to..."

Plan on several days for optimal sound with solid state devices.

Several days? That's just silly...turn off everything when you're not around, or at least never admit that you leave things on, as these days that's simply lame. Really.

A point that I don't think has been mentioned yet is that depending on the specific design leaving it on all the time might result in greater long-term reliability than turning it on and off, especially if that is done frequently, as a result of reduced thermal cycling.

I use the phono section of a vintage Mark Levinson ML-1 preamplifier as my phono stage. The ML-1 has no power switch. Although I am not its original owner I know that it has been powered up for essentially all of the past 35 years, and its phono section works as new. (Its line stage, which I do not use, did develop a problem a few years ago after being powered up for 30+ years).

However if you do want to turn off a phono stage having no power switch, without turning off power to your tuner or other components, just get a power strip (one that is just a power strip with a switch but includes no filtering or conditioning) and plug its power cord into one of the outlets on your existing strip or conditioner. This Hammond model would be a good choice, if its physical size is acceptable to you.

Some folks might assert that doing that would adversely affect sonics, but IMO any such claims would be speculative, technically unsupportable, and unlikely to be based on experience doing the same thing with the same or similar equipment.

Regards,
-- Al

What Al said.
I nearly never turn off the solid state components in my audio system. The OP did not say whether the phono stages he is considering are solid state or tube type (or maybe it came out in subsequent discussion which I have not read). The AV receiver in my home theater system has never been shut down since new (about 6 years).

However, most of my gear is tube type, and I do shut down all that stuff between listening sessions, even though I know that turn-on places certain stresses on tubes and the components that feed them.