Hi,
I have attached some images of my prototype music player running volumio.
Main elements:
- Closed frame AC/DC converter
- Raspberry 3
- Hifiberry digi+ pro
- 128Gb USB stick for music files
A/D conversion is done by the existing Onkyo receiver, the only purpose of the device is to stote the music files, acting as a NAS - and converting them to a optical data stream for the following chain.