I made an unconfirmed as yet observation about using the WDM driver, which may assist others in solving stuttering problems.
I wanted to use Airplay to mirror an iPad onto my HTPC and use MC's WDM and DSP including Room Correction to play the audio. So I installed "Air Server" on the HTPC to enable it as an Airplay receiver. The iPad was being used to play Plants vs Zombies 2, so the stream had lots of sound effects rather than a continuous stream like music.
The audio worked, but it was stuttering, or maybe "broken up" is a more correct description. Anyway, after lots of fiddling around, changing back and forth between the real device driver and the JRiver WDM I discovered that if I set Air Server to output to the "Speakers, JRiver Media Centre 20" I got bad audio, but if I set Air Server to output to the Default Windows audio driver the audio was fine. No issues at all. Of course the MC WDM was set as the default audio driver in Windows.
So for those having trouble with the WDM driver, if you are selecting it in your application, try setting the WDM Driver as the Windows default (as advised above) and selecting the Windows Default device in your application instead, if possible. This worked for me.