Hello Lancaster, thanks a lot for posting your question at Intel communities.
It is important to know that the Audio playback through HDMI is managed by the HD Graphics driver but in our case we only include the core Graphics driver with a Control panel and the base HDMI codec so the audio can be transmitted through the HDMI.
If you want to modify the sound when playing back an audio file or movie, usually the playback program (Windows Media Player, Cyberlink Power DVD, Real Player, Nero Media Player, Winamp, etc) offers Equalizers or effects that you can use.
I'd suggest you to check the audio/video playback tool you use to see if it offers an EQ or Fx area.
Thanks for your fast answer.
You are more than welcome !