Hi Mark,
1. Some specific Denon model receivers allow you to do just that, from all their analog outputs. At least from my understanding. And because, I was exactly looking for that very specific feature, same as the OP, for several years now. So, I did extensive research in that matter.
2. Yes, I'm pretty sure that works. At least from what I know.
3. I mean what I said; ADC (with the help of DAC). They work in tandem for that situation.
4. I do. Just go to Denon own web site. You can even call Denon technical service support department, and ask to speak to an engineer that knows.
* By the way, this is not all what I know; I keep an arsenal in my lockers.
Best regards,
Bob