Sprout100 static sound with thunderbolt

I found that when I connect my MacBook Pro to my monitor using the thunderbolt cable (which supplies power and video to and from the MacBook) and USB out to sprout100, there is a static sound generated with this setup. It produce no static sound if I connect to a power outlet for just power only.

is there any way I can “clean” the signal, so there will be no static sound when I plug the thunderbolt to the monitor?