You can only use an input-output loop if the receiver has "tape monitoring" -- as far as I can tell by looking at the picture of the front of the R-N803, I don't see a "tape monitor" function, but maybe I'm missing it.
The tape monitoring allows you to listen to a recording as it is being made; therefore, you can set it for monitoring, and modify the CD signal through the tape loop as you listen to it. But without tape monitoring, it won't work.