I think they are small and cheap and if you can’t hear it you can’t hear it.
This is the brand I use. You can even schedule it to turn itself off at specific times or events like sunrise/sunset.
I don't have one on my listening gear per se, but I have about 14 switches and smart plugs around the house and I definitely can't hear them degrade the sound. If anything, compared to the old school dimmer switches I think they are a lot quieter physically and electrically.