Circuit Buzz?

[Stevoster]

Hi all,

I'm getting a very annoying high pitch buzz (on recorded audio) when I create a circuit with my piano. I have a protools midi channel with the piano notes which I send to my piano (Roland HP505), then I run the piano output into the laptop (windows, via MBox 2). When I disconnect the usb connection the audio feeds perfectly (obviously I have to play it manually as the midi is no longer sent to it) but as soon as the usb lead touches any metal part of the laptop the buzz starts. So I have isolated it as some sort of electrical current / circuit that needs to be fixed. Is there some way to remove it? I tried running the laptop on battery instead of mains but no difference. Obviously I don't have this option with the piano. I have disconnected all other power cables

Apologies if this is the wrong forum for this - any help would be very much appreciated. Driving me nuts! I'm in Ireland and my mains connections are grounded (I think!).

Thanks,
Steve.

[Darryl Ramm]

Classic ground loop symptoms.

Do all the usual ground loop mitigation things.

A good detailed explanation of what causes this and how to address it is here https://www.youtube.com/watch?v=GS-6jBk9YPM