@Thatsthestuff, you probably have already found this out if you got a Modi/Modius, but your comment is
almost accurate: the Modi/Modius will pass through the digital source input volume level to all outputs EXCEPT when the input source is connected via USB.
Example 1: Blusound Node streamer --USB--> Schiit Modius --XLR--> Schiit Freya+ preamp --XLR--> Parasound A21 amp --> B&W 702s2 speakers and the volume setting on the Blusound Node has no affect on speaker volume level.
In contrast, if I replace the USB connection with any other option (coax, optical, RCA), the volume adjustment on the Blusound Node (digital source)
does affect speaker volume level.
Example 2: Blusound Node streamer --coaxial--> Schiit Modius --XLR--> Schiit Freya+ preamp --XLR--> Parasound A21 amp --> B&W 702s2 speakers
And for what it's worth, the fixed output level in example 1 (USB from digital source to Modius) is too high to work with my Freya preamp, as even at the lowest preamp volume setting, the speaker sound level is well above "quiet/silent".