Halo CE audio just started crackling & won't stop

I’ve been playing Halo CE since it came out for MCC on PC, but for some reason, the audio just started crackling. Seems to be focused around weapons fire and other sound effects (grenades and such). I have over 500 hours in MCC, and this just started out of the blue. Any suggestions? I have tried verifying integrity of game files, restoring settings, restarting my PC, trying some alleged fix I found on youtube, changing the audio quality of my output device, and reinstalling the game, but to no avail. I don’t understand why this would just crop up randomly, and mid game session no less!