I am trying to connect the following: Marantz SR7000, Explorer 8300HD DVR cable box, and Mitsubishi WD52525 but I just don't get how to set it all up. I don't understand how to connect the digital audio output from TV to Marantz. The cable box is connected via HDMI,but I'm unable to get surround sound, only stereo. The initial set-up instructions have me select the TV input on the Marantz, but doesn't really explain that step and how to then select the digital input. Any help would be appreciated.Thanks.