Can't play audio CDs without having the TV on

Your description is not entirely clear, so I have to guess a little here, but I think what is happening is as follows:

1) You are using your DVD player as the source for the CD.
2) Your DVD is connected directly to the TV and the TV then connected to your receiver.

If the above are correct, then the problem is that the TV only has what is called an ACTIVE passthru for Audio signals. This means that the signal is process by the TV and tehn sent to the audio output jacks. With the TV off, the buffer ICs are not functioning, thus no output. Some older sets have what is called PASSIVE passthru.

I don't know your specific DVD model specs, so check to see if you have 2 audio outputs from the DVD (many do) and connect the other audio out directly to the receiver. That will resolve your problem.

Dan