Tccaux,
Just curious, did you try disconnecting the Cable Company's CATV coax cable from the cable box and see if that stopped the hum? If not all you did was break the ground loop circuit by installing two ground cheaters in the AC mains safety equipment ground.
IF the ground loop problem is being caused by the Cable Company's CATV coax cable that means the lightning protection grounding block on the outside of your house may not be properly grounded to the main grounding system of your home.
If it is the CATV coax cable causing the ground loop problem this will also break the ground loop and stop the hum. It will not correct the CATV coax cable grounding problem though.
http://www.amazon.com/Jensen-VRD-1FF-Digital-Isolator-Jensen/dp/B00AQV04FE
Just curious, did you try disconnecting the Cable Company's CATV coax cable from the cable box and see if that stopped the hum? If not all you did was break the ground loop circuit by installing two ground cheaters in the AC mains safety equipment ground.
IF the ground loop problem is being caused by the Cable Company's CATV coax cable that means the lightning protection grounding block on the outside of your house may not be properly grounded to the main grounding system of your home.
If it is the CATV coax cable causing the ground loop problem this will also break the ground loop and stop the hum. It will not correct the CATV coax cable grounding problem though.
http://www.amazon.com/Jensen-VRD-1FF-Digital-Isolator-Jensen/dp/B00AQV04FE