If your speakers are making a humming or buzzing noise then you quite likely have a ground loop issue.

This happens when electrical devices on separate circuits are "connected" via a low voltage signal cable such as when you connect a television to an amplifier with an RCA cable.

In HiFi systems it can often be fixed by simply plugging all equipment into the same socket via a mains conditioner extension lead.

For everything else there's ground loop isolators!