On Sun, 6 Oct 2019, Gene wrote:

If you want the NVDA audio to go through the USB soundcard, you would set NVDA to use that sound card.  This is done within NVDA itself.
But I don't know how you direct the other audio to use the original internal sound card.  Others would have to answer that.  I've never tried such a
setting.

Would you not just set the internal card as the Windows default?
I have certainly done the opposite before: set a USB card as Windows default, and set NVDA to use the internal card, so I don't see why the inverse wouldn't work.
Luke