I'd like to add my voice to the incredibly tiny crowd of people who would love to see this. I love my audio system, MusicBox to Mopidy to SnapCast (multiroom) to Pi clients with HiFiBerries. But if someone came over and wanted to play CD through the system (and therefore through the house, I'd have to sadly shake my head.
Thanks Adamcik for the reply. Despite the computer science degree and past life as a Windows C/C++ programmer, I am nowhere near ready to tackle this yet.