Very, very good questions.
Primarily, I want something transparent to sit between my PC and headphones, with no danger of ground loops.
I’ll be using it in my office. I have a cheap Denon receiver and a pair of Monitor Audio Bronze bookshelf speakers. They are currently driven by an old FiiO DAC, and I’m happy with what I have there.
So Bluetooth and other inputs and outputs might potentially have some use which I don’t currently foresee, but aren’t necessary. Truth is, a D10S, which I can pick up later, would be more than fine for that, cheap, not urgent, and more than I really need.
Right now it’s about sitting at my desk with my headphones on (Sennheiser HD600) with the best quality (that’s best quality that I can actually hear, rather than measure) for the lowest price.