Thats bad for the environment and your electricity bill. My Leak Stereo 130 turns off after 15mins if no signal (except in turntable setting I turn off manually). My TUK system also automatically turns off.

A soft foam pad 1/4" between the speaker and the plant for sound isolation, a dish under the plant pot (to catch any runoff) and I can’t see the harm in this to the speaker or sound quality.