In JRiver go to
Tools > Options > Audio > Audio Device and from the dropdown under it select
YourUSBDAC [WASAPI]The click on
Device Settings and look at options you may want to enable such as
-
Open device for exclusive access (will disable any other system sounds during playback)
-
Maximize device volume during playback (if you will be using an analog volume control downstream)
And under
Settings -
Play files from memory instead of disk - Under
DSP & output format you may want to customize downsampling if you have files with higher sample rates than 96KHz.
Because my DAC is 24/96 (like your Schiit Modi), I left all sample rates up to 96KHz unchanged and downsampled 176.4KHz to 88.2KHz (even multiple) and 192KHz to 96KHz.
Take a look at the rest of the various settings on the JRiver Audio options page to customize how you want the player to operate.
Steve