WiiM Pro optical ground loop

[ummduh]

Lately, I've been getting a pretty bad ground loop hum. It wasn't there when new, I've had this about 6 months now.

I exclusively listen to this via Chromecast to my old Yamaha home entertainment receiver.

All of a sudden it developed a pretty gnarly ground loop hum when I turn the receiver on, until the Chromecast connection happens. Once it's connected to Chromecast the hum completely goes away until I disconnect.

I have to connect with Chromecast, and then press play, and as soon as I press play the hum goes away completely.

I dont have other circuits to try, I have a single circuit serving my garage.

It is plugged in to a multi plug adapter deal (not a surge strip). But like I said, this developed quite a while after initial installation. I haven't changed anything.

Any ideas?

 

[Mr Ee]

Welcome.

So the only connections into the Yamaha are the mains and the optical from the pro?
Does the yamaha start on a different input and auto switch to the optical when you play to the pro?

 

[Horsey]

You should switch out the optical cable and start there. Put in a nice glass toslink cable. They are not expensive these days.