🚀 go-pugleaf

      That suggests that the new sound card or computer may be the source of
      the problem. But I've thought this through and can't come up with any
      theory that could explain how anything outside Audition, either the sound
      card or Windows, could explain this discrepancy.




Except that presumably you installed a new driver with the new soundcard, and since that accounts for everything that gets sent into the system from the card, I'd say that it was pretty a fundamental source of potential difficulty, myself!

The most likely explanation though is that in the hardware setup, (Options>Device Properties) you haven't got a tick in the box for the driver that you are using in MV that says 'use in EV', and that in EV you are using some sort of nasty default device, like wave mapper. That alone could easily account for the discrepancy...