Hi, I'm also curious to hear the results of the test.
Another possibility for connectivity between the Synology and the NAD would be to use an USB optical output dongle connected to the NAS, with optical running to an input on the NAD. I was searching around to see if others had success with one of these, and stumbled on Synology's version, which even comes with a remote. No idea how well it'd work, but its definitely intriguing!
Synology - Network Attached Storage (NAS)