Your assumption that HDMI should provide sound was correct. It is an "all-in-one" cable for Audio and Video. I apologize, but I totally forgot about your HDMI connection with my first response. It should really simplify the connection. One HDMI from DVD to Denon, then one HDMI to LCD. Most HDMI supports DVD-A, but perhaps not SACD. As MNNC stated, also connect the RCA's to the DVD and Receiver. However, you should get sound from DVD's without the RCA. IF you are not, you need to make sure your DVD and Receiver are set to accept the HDMI cable. Check your setup and play around until you get sound from the HDMI. You don't really the the upconversion of the receiver for the video, but since you already are running the HDMI from the DVD to the Denon, it is just as easy to run the HDMI from the receiver to the TV. I doubt you will have any noticeable decrease in quality by going through the receiver. Some purists suggest bypassing the receiver since often times the more you change the signal or add in-between components, the more chance of signal degredation.
Roly