I generally don’t like to necro threads, but as I was running into the issue myself I wanted to give an update.
I was gone for about nine months from July of last year to April 2022. When I came back, I was experiencing what felt like surround sound despite having stereo speakers. In the time period between I did upgrade to Windows 11. Sure enough, some of the previous solutions listed didn’t work.
With a bit of trial and error I managed to fix it. If you’re on Win11, head into your system settings, then click on sound. From that menu, look under the header for output and pick the device you generally play WoW’s audio from. Click on that (the heading at the top of the window should be System>Sound>Properties)
Under output settings, you’ll want to set Enhance Audio to off, as well as the Spatial Sound setting. If you have WoW running when you do this, chances are all volume within the game will go mute at this point. Go into the sound settings within WoW and change the Game Sound Output to anything else (doesn’t matter). Afterwards, swap it back to your original option. For example: on my system I changed WoW’s output to my monitor speakers, then swapped it back to my external speakers. That got the audio running again and also eliminated the pseudo surround sound effect that becomes highly noticeable on only two speakers.
Hope that helps someone out should they run into the same issue.