Buzz, Hum With Directv?

Hi guys. I hope I has posted this in the right section. I have a buzz or hum through my speaker, and the noise goes away when I unplug the HDMI from my Directv box. I went outside to check the ground and the ground on the coaxial cable is grounded to the Directv grounding block, and then there is a ground coming off the block that is connected to a clamp on my meter. Is this a sufficient ground? Could this be causing my issue?