How do I fix a loud buzz on my headphones

Factual Questions
1

I use Headphones and a microphone for SKYPE. I get a loud buzz on them. I have tried two different pair and get the same buzz. I’ve tried 4 different machines and get the same buzz. I keep thinking I have something set up wrong.

Any ideas?

2

Might have a ground loop. Those are sometimes hard to track down, but you can start by making sure there is only a single path to ground for all the equipment. A ground loop happens when the chassis of unit A is connected to that of unit B and each has their own chassis connected to the building ground (usually via the power cord.)