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.

 

[ummduh]

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?

Correct, only an optical cable, and besides power, optical is also the only connection on the WiiM.

No, the reciver stays on "optical in" at all times.

The WiiM replaced the original chromecast audio that google bricked a while back, its the only thing on the receiver. Never had a hum with the cc-a (and it was on there for a LONG time)