You can indeed use the new Dolby Atmos/Windows Sonic sound formats with your Astro Mixamp. But it’s a little more complicated than just picking the stereo uncompressed setting! Here’s a guide just in case.
Navigate to the audio settings on your Xbox One (sorry for lame cell phone picture of my screen).
Set the Optical Audio setting on the left to stereo uncompressed.
Next, under headset format on the right, select either Windows Sonic or Dolby Atmos for headphones.
Next, make sure you select the checkbox next to “Using HDMI or optical audio headset.” This will send the surround-processed audio to your Mixamp, instead of your controller’s audio port.
Finally, make sure the Dolby Headphone button on the Mixamp itself is set to off, so that the red light around the Dolby logo isn’t illuminated. Otherwise you’ll be re-processing the already-processed sound, and it won’t sound good at all.
Note, if you select Dolby Atmos, you’ll need to download the Dolby Access app. It offers a free trial, and after the trial expires, it’s only 15 bucks to keep it. Windows Sonic is free, and always will be as far as I know. It’s pretty good too!
I can’t say whether you’ll like either of these more than the Dolby Headphone processing built into the Mixamp, but I bet you’ll still have a fun time trying them out. I think all three options provide very different and equally valid experiences. I’ve actually found myself liking Windows Sonic the most in certain games/movies. Audio listening is pretty subjective, and these virtual surround technologies are going to work a little differently for every listener just because of the way they’re designed.
Hope that helps you out! Thanks for reading!