I strongly recommend to all those out there that are experiencing hum on their speakers or subwoofers to install an in-line ground isolator on their cable feed. And I recommend this even for those that have cable installed but may not be using it.
I've had a slight hum on my EP600 since I bought it. I had cable outlets installed and wired but did not have my cable connected to any of my components. I recently had my cable service turned on and the hum on my 600 continued and it also appeared on all of my other speakers. After installing the ground isolator, the hum disappeared.
The very peculiar thing that I've noticed (and cannot readily explain) is that if I disconnect the cable from my components and remove the isolator, the hum re-appears on my 600 (but not on any of my other speakers). If I install the isolator, the hum disappears.
Your cable company will supply and install this isolator for free. Just make sure that this isolator is not located on the cable branch that is providing you digital phone service.
