How do I prevent external speakers from going to sleep?

I have the Harman Kardon Soundsticks III and like most (maybe all) of the remaining quality desktop external speakers their Energy Star conformance means they switch off after 30 minutes of no sound signal and can take a lot of cajolling to get going again. You play iTunes, nothing happens, you receive notifications, no sound etc. until you press this and that and eventually you get sound, again. Preventing the Mac from going to sleep (hardly ideal) doesn't work as it will still stop sending audio.

The same problem is described here https://forum.polkaudio.com/discussion/164112/hampden-desktop-speakers-any-way-to-disable-sleep-mode for a different set of speakers. There seem to be two fixes: one that implies only speakers that have a USB connection (mine don't) and another is a clever piece of code for Windows that a user wrote just for this purpose.

Does anyone have any solutions or failing that, know of good speakers that don't suffer from this Energy Star affliction (giving environmental regs a bad name, in this case).

Thank you!