I installed 2 DVD headrests in my wife's Jeep Liberty. I connected both of them to the fuse box via an Add-A-Fuse. I made sure both were grounded correctly and all wires were good. The problem is, I only have a hum or buzz in the passenger headrest when the car is running (there's a slight noise when I only have the ignition on battery, but barely noticeable). For troubleshooting; I connected a portable DVD player that I hooked up to the passenger DVD headrest, and it played with no buzz. I also used it to display what was playing on my driver DVD headrest - no buzz. I noticed when I unplug the 3 RCA cables connecting the 2 DVD headrests, the buzz stops - that's why I was testing using the portable DVD player, for both situations. I tried different fuse locations, I tried different ground locations (where it's at now is the best). I tried separating the RCA cables and power cables ... I can't find out why I'm getting the buzz in only the passenger DVD headrest.
I'm thinking about taking it to our local audio/video place in Indianapolis for help, but thought I'd share my situation online in hopes of an answer.