I have just replaced my auralic streamer/upsampler with the Vivaldi Upsampler as the digital hub for my system; comprising Naim UnitiCore as the source for my ripped Cd’s, Roon Nucleus+ for streaming sources, Tidal, and internet radio plus library management and Dutch & Dutch 8c loudspeakers. All running latest software. My issue is how to control volume. Ideally from either Roon or the Vivaldi. I could do this with the auralic based system however having introduced the Vivaldi I’m left having to use the 8c volume control. In Roon and either Mosaic/Vivaldi apps the volume shows as -80dB but the volume slider does not affect the sound level. Almost certainly user error so can someone get me pointed in the right direction please 
Ian, the Vivaldi Upsampler has no Volume control capability as it’s designed to be coupled to a Vivaldi DAC which is where the Volume control function resides.
Since you’re utilising the 8c’s built-in DAC, IMHO, it’s best to leverage the 8c’s volume control, rather than truncating the digital source stream (Roon).
Thanks Anup