If there's no sound from the left and right channels, the most likely problem is with the left and right analog connections from the Denon to the 970. Those connections should be from the left and right channels of the Denon's 5.1 analog output to the left and right channels of the DVD input (the ones at the bottom of the rear panel, below the DVD input's s-video connection).

Are you setting the 970's DVD input to always use the 7.1 direct input, or are you just toggling to the 7.1 direct input when you want to listen to DVD-A and SACD? If you are toggling, you may need to be on the DVD input before you try to toggle to that input. I would recommend setting the 970's DVD input to the digital input that you used (coaxial or optical) and use the "7.1" button (near the middle of the remote, bottom left corner of the navigation pad button area) to engage the 7.1 analog input when it's needed - after selecting the DVD input first (both so you have the desired video input active and because the 7.1 direct's left and right channels are associated with the DVD input).