Yes, I ended up having to disable the JRiver volume altogether and setting the windows volume at 100%.
This was the only way it worked for me in Windows 8.1 Pro N.
Is there any reason why this can't be part of the NuPrime documentation? It would certainly make for a more pleasant 'new ASIO user' experience.
Showing how the DAC 10 works with FooBar is great but doesn't really apply to other platforms and media players.
Better still, program the driver accordingly...