surfgeorge
Member of the Trade: 3D Printed Accessory Designer
That's with your setup using the micro-USB cable from the R3 to the Mojo.I stand corrected. I thought it would be like the first photo, but I know what you mean now as in the second one. Just tested it myself due to curiosity. The digital volume does not affect anything.
When you use the USB-C to Coax cable, the R3's volume control changes the digital signal going to the Mojo. In that case you need to make sure it's set to 100% on the R3.