I started using a portable speaker for my Windows computer, and after discovering it goes to sleep got the following explanation from the manufacturer:
That model, as well as the rest of our portable speakers, has a power-saving feature wherein it will automatically enter the Standby mode after it detects no audio or no actions received for 10 minutes. And there are no options to disable the power saving/sleep mode.
So I want a script or program that will play an inaudible tone (e.g., over 30kHz) at least every 10 minutes. But the tone has to be low-volume, or fade in and out, to avoid making the speaker click when it starts.