Owner`s manual

The Windows mixer will be shown. If more than one soundcard is installed in your
computer, the USB Audio Device must be selected in the Windows mixer. To do this,
simply select the Options/Properties menu item:
and in the next window select USB Audio Device and the Playback section.
Enable the “Master Out” and “Wave” checkboxes and disable all other ones.
X4 Owner's Manual - Rev. 1.4 - page 16