Whipsaw,
As swampwalker said in his post the disc inputs are phono inputs.
You do have two other line level inputs available on the amp though.
The two tape inputs RCA jacks on the rear panel. Tape 1 and tape 2.
Connect the AV source to one of the Tape inputs.
On the front panel press the monitor button you connected the AV source to. 1 or 2.
I notice there is a "Source" push button to the left of "2" and "1"
You may have to press, engage, this button as well. Not sure. The instructions in the Link below are vague.