When you select music to play in MC it will be passed via IPC to the WDM Driver which will allow the application of DSP studio settings and then on to your audio output device.
That statement is a bit confusing. To clarify:
When you select music to play in MC it will be played directly in MC and output to the Audio Device selected under "Options > Audio > Audio Device", and will use the Device settings and DSP as defined under "Options > Audio".
When playing any audio from an
external source, where that source is able to select the WDM as an
Output, or the WDM is selected as the default Windows Playback Device and the source is playing to the default Windows audio device, the WDM is then the
Input to MC. MC then plays that audio to the Output device selected under "Options > Audio > Audio Device", and will use the Device settings and DSP as defined under "Options > Audio".
So;
External Source > WDM Driver > JRiver Media Center (including DSP if defined) > Output Device defined under "Options > Audio > Audio Device".
The key point is that the
WDM is an Input to MC, and should never be selected as the Output under "Options > Audio > Audio Device". Also, when the WDM is selected as the default Windows Playback Device, the Default Audio Device should never be selected under "Options > Audio > Audio Device". Doing either would create a positive feedback loop if MC wasn't smart enough to mute the output, which is what it does.