Arindelle, thanks.
So if I used an optical in, what would that connect to? My MacBook?
What are the advantages of optical v USB?
Mac Pro Optical Out (if it has one, I presume it does) => Denon Optical IN; if not USB (see below); Regardless you want to use MC as the renderer and not push to the Denon via DLNA
Simple answer : ) If the DAC inside the Denon uses an asynchronous connection - its (probably) better to go USB as asynchronous cnnx (tend) to reduce jitter. As this is an "all-in-one" unit, and in their specs async is not indicated (which would be a selling point), I'm presuming this is a normal USB connection which is jitter prone - call it "dirtier". So I'd say that optical would be a better "cleaner" choice. I've heard that Macs are cleaner than PCs, but I imagine it works generally on the same principals (don't have a Mac
)
If the DAC is half way decent, the cost of an optical cable is not much compared to an external DAC, so you might want to try this first. If the DAC inside is accetable to pretty good - you might have to spend pretty much the cost of the Denon to make it appreciably better.
What you could do is find a shop that sells your Danon and some external DACS and compare them using your mac/music. If the DAC in the Denon is really bad however, there are some very reasonable DACs on the market starting at about 100USD.