Hook up BOTH digital AND analog to the receiver. When the receiver is hooked up only in digital, it will play the digital format it detects...which is usually DD (unless DTS, DD 5.1 etc). If it is hooked up in ONLY analog, it will play in only analog which then you can use the different selections of the receiver, but then you CANT use DD, DD5.1, DTS, etc...
If you hook up both, you can use all the features of the receiver by switching back and forth between digital and analog. eg...switch the input on the receiver from the digital input (coax, or optical) and the analog input for the specific source. Just as Ironmike suggested, switch back and fourth to your desired format.
I do the same thing when watching SOME DVD concerts!