Here is, how you get sound out of the DA7:

Images are clickable

After you made the necessary connections on the patch bay(s), dial "01" on the number keypad on the DA7.
Slide the fader up to unity gain (0)
Activate the channel put pushing the "on" button (it'll light up red)
Now go to the Main section and push the L/R button (this assigns the channel to the stereo output of the DA7 (button will light up green)
Still in the Main section push the other L/R button to activate the DA7's stereo out
Set the red Main fader to unity gain
Finally adjust the gain (preamp) to your desired level