Audio hum

My wife and I have noticed a hum in our whole house audio system and today I finally decided to do a web search and see what came up for fixing it. I found an article which indicated that any component hooked up to cable TV could cause the problem. This sounded far fetched to me, but what do I know about audio and intereference? So, I disconnected all but the MP3 player and the hum went away. I plugged in each source until I got to the TiVo/TV. When I got to the TiVo/TV (it’s on a switch), the hum came back. So, I disconnected the cable and what do you know? The hum was almost eliminated! Now I’m off to the store to look for an isolator to fix the problem. I learn something new everyday.