Hey Jason,

 I just tested some things out.

When I walked into the sound room, our Xbox360 was feeding digital audio out to the receiver via an optical connection. I turned off the TV and nothing happened. This is what I expected.

I then turned on the Blu-ray player half expecting the Onkyo to switch to the Blu-Ray input. It did not. I started a CD in the Blu-Ray player and saw that it was running. I switched the Onkyo to the Blu-Ray input and the Blu-Ray player reset to the main menu as I expected it to. I got the music playing and all was well. When I turned the TV OFF, the sound disappeared.

It appears that the HDCP protocal is the issue. Here's what I suggest:

If your DVD player has an optical connection (or coaxial) in addition to the HDMI connection, you could run that to one of your Onkyo's inputs for CD audio without having the TV on. There will be a difference in sound quality between running a digital signal and an analog signal. Unless you have a mighty nice player with premium DACs built in, the Burr Brown DACs in your Onkyo should be superior and provide the best audio.

As for running Optical from your TV to your receiver: This will be fine in most cases, but if you want to hear Dolby Digital Tru HD or DTS Master HD tracks on Blu-Ray movies, then you must use your HDMI connection to the receiver. Those formats will not pass via an optical connection.

Hope this helps!

CD