Virtual Desktop WILL receive audio that was routed to the ORIGINAL windows default device, however, this solution has a problem: When selecting 'Speakers (Virtual Desktop Audio)' in Voicemeeter as the output, Virtual Desktop will not actually receive the sound being routed to that audio device. So routing audio to 'Virtual Desktop Speakers' will not produce sound. The issue, is that 'Virtual Desktop Speakers' doesn't act like an audio device that can receive audio.

That's strange, but that's not the issue. What's strange, is that I can manually change the windows default sound output BACK to the original, and Virtual Desktop will still receive audio. I believe that when Virtual Desktop starts, it checks the default windows sound output, changes the default to itself, and then forwards the audio to the original default sound output. However I can't get Voicemeeter to output audio to Virtual Desktop even when I select 'Speakers (Virtual Desktop Audio)' as the output for Voicemeeter. I use Voicemeeter to mix my piano, mic, music, default sound, etc.