Hi,
The X40 do not see the DSD file that I placed on the Synology NAS.
DSD files standing on the HDD is no problem. I would like to play DSD files from my NAS.
Could it be, that you work over UPNP? UPNP don't support this kind of file type. You have to connect to the network share...
I'm afraid my NAS (DS209) is to old. I read on the internet thats it must be working with MinimServer. I can't install this, because the NAS and the OS is an old one...
Maybe a good reason to buy a faster NAS with an up to date OS

speed should be not the problem. So do you access via UPNP or SMB/Samba share?
Than it's a clear problem of your UPNP Server. I currently don't know any UPNP Server, which can deliver this file types.
Finally its working via Samba/Network share and it sounds realy great!!