Is the dCS Lina in your main system and you have something else upstairs? Do you want access to the same SSD of music files both upstairs and downstairs? If yes, then you need that library on the network. Just checking online, this looks totally doable with Innuos.
Do NOT assume though that you can pop the SSD out of the ROCK and use it elsewhere. Get a second SSD… maybe a portable USB one like from Samsung… and download all the tunes from the ROCK over the network.
You could then test just using the dCS app with the USB SSD attached to the Lina to see if that works for you… just with the dCS. If you are OK just to have streaming upstairs, then this might do.

