Audio signal from usb audio card to trigger relay

Hello everybody, I'm very new to the forum and to electronics in general. I've searched the forum for this question, but I couldn't find anything strictly related.

I have made a Squeezebox out of a Raspberry Pi, and it works great. I'd like to go one step further though... the situation is as follows: the RPi is powered by a USB Hub, to which a USB audio card, and USB Speakers are connected. The audio card output goes to the USB Speakers.

Unfortunately the speakers stay on all the time, though, and this is not good for their longevity... Therefore I was wondering whether there was a way to make some kind of gizmo that "monitors" the audio output and powers on the speakers only when they are needed (basically when music plays). And, of course, that powers them off when the music stops.

I've read about the so-called clap circuits, but that does not really look like the same thing. Any help would be appreciated.

Oh, btw... I also have an Arduino nano, if needed :)

Thanks, Luca

There is no need to use an arduino you can use the Raspberry Pi. Therefore you are best asking on their forum.