Ground Loop Problem - 2 computers, 1 Amplifier....HELP!!!!

[Guitarman0]

I have been having this ground loop problem that's driving me crazy! Basically my PC and my mac are both plugged into my amplifier. When they are both plugged in together and I switch the audio source to my PC I get a horrible buzzing through the speakers, but as soon as I disconnect my mac the buzzing stops. I have tried changing both of the cables from my pc to my amp and my mac to my amp and I have also tried using an external audio input switch (to ensure its not just the one in my amp) but I still get the problem.

Any ideas?

Cheers

 

[Guitarman0]

In case anyone is interested I managed to fix the problem by connecting a ground loop isolator to the mac input on the amp.

 

[Marsman]

Glad you got it sorted.

How did you come by the solution?