Thanks to everyone for the help getting my HT off and running. Amp is set, Z4 is callibrated, Carada screen is hung, and then......the Scientific Atlanta 8300 HD box is the wrench. I hooked up the box via optical for audio and comp for video. This is when the ground hum starts when the comp video is hooked up to my amp. If I just have the optical in there is no hum, only when the comp portion is added. I was going to run HDMI direct to the Z4 (bypassing the amp). Anyone have another sugestion? Thanks Chris

I have my DVD/HDMI cable directly to my Z2.

thanks for the reply. I called the cable company and they didn't know what a ground loop was....Scary. They wanted me to return the HD box for another. I decided to ground every splitter in the house and that solved the problem.