Audio monitoring buzz related to ML graphics on screen

[quickreactor]

Hi,

Just updated to 2.3 Unified on my 60D and have noticed an annoying new problem.

When I am using things like focus peaking - magic zoom etc, basically anything that brings up little patterns on the screen, I can hear a buzz in my headphones, which are connected via the usb cable with the red and white RCAs adapted to a single headphone in slot.

When I bring up the menu or anything pure black or flat colour, it stops, and it doesn't come up in the recorded footage which is great, but it means it's something to do with the output of MLs audio. However I am very keen to fix it because it will make it more difficult to ascertain other audio problems via the headphones.

Can anyone help or suggest anything? Have I just got a setting wrong somewhere? I will try anything you suggest and report back so that other with the same issue may benefit.