Massive feedback through L/R on PC with Lyngdorf 1120?

[famasfilms]

So my system was an Nvidia GTX 1650 Super connected via HDMI to a Denon 6500.

I added a Lyngdorf 1120 earlier, connected it to the preouts of the Denon to drive my L/R speakers. I played around with it for a bit then did a factory reset (because I bought an open box unit)

Since the reset I've had massive feedback / interference through the L / R speakers when using the input from the Denon. Moving the mouse makes it louder. Unplugging the HDMI cable from the GFX card to Denon makes the noise stop - but then I don't have sound through my L/R when using the PC.

I moved all the devices around and made sure the L/R speaker cables etc were away from the HDMI and any power leads but no idea what is causing it

 

[JayGilb]

So my system was an Nvidia GTX 1650 Super connected via HDMI to a Denon 6500.

I added a Lyngdorf 1120 earlier, connected it to the preouts of the Denon to drive my L/R speakers. I played around with it for a bit then did a factory reset (because I bought an open box unit)

Since the reset I've had massive feedback / interference through the L / R speakers when using the input from the Denon. Moving the mouse makes it louder. Unplugging the HDMI cable from the GFX card to Denon makes the noise stop - but then I don't have sound through my L/R when using the PC.

I moved all the devices around and made sure the L/R speaker cables etc were away from the HDMI and any power leads but no idea what is causing it

What are you using to connect the Denon to the Lyngdorf ?
Have you tried different hdmi inputs on the Denon ?

Sounds like a very bacd ground loop, since you can hear the mouse movements from the GPU.
Does it sound more like feedback or a 60hz type of hum ?

 

[famasfilms]

What are you using to connect the Denon to the Lyngdorf ?
Have you tried different hdmi inputs on the Denon ?

Sounds like a very bacd ground loop, since you can hear the mouse movements from the GPU.
Does it sound more like feedback or a 60hz type of hum ?

Just rca cable from Amazon.

Have tried different HDMI inputs.

Have unplugged every unneeded device (e.g. Hire hue bridge and lights etc) and plugged PC, denon and lyngdorf into same surge protector

Don't know what else to try

Even in lyngdorf settings, if I increase volume of the avr input there's audible buzzing

Just now when I turned on pc, it was very similar but not exactly the same as the 56k modem connecting to the internet noise

 

[JayGilb]

Maybe try a quality audio isolation transformer (rca to rca) between the Denon and the Lyndorf. ?
I don't see any optical outputs on the Denon and am unsure if it could me programmed to to only send L+R and volume control would be a problem.

Not sure where you're located or your budget, but something like CI-2RR Isolation Transformer might work for you.
A lot of people do not like audio isolation transformers, but they do work in certain situations.