From the owner's manual for a new Pioneer receiver.

Keep in mind you can’t make a digital recording from an analog source or vice-versa, so make sure the components you are recording to/from are hooked up in the same way (see Connecting up on page12 for more on connections).

I wonder why that is? I suppose this is what HDMI cables, etc, are all about. That is, if the signal stays digital, not only does it not degrade [in theory], you can continue to DRM it.

Still, the speakers aren't putting out digital. Why can't I copy my digital files with an audio cassette?