Solved! Games with surround sound are significantly quieter than those without.

[JackMateo123]

Somehow, out of nowhere yesterday (or probably when I accidentally reset to the Microsoft recommended settings in the app volume and device preferences, any game (CSGO, PUBG, Rust, Siege, etc) that has surround sound is very quiet and needs to have both in-game volume and master volume to be at 100% for it to be slightly loud in audio. Games without, such as TF2 and GMod, sound perfectly clear and blast your ear drums at 100% max volume (indicating they are fine).

I tried reinstalling/uninstalling/the whole shebang for audio drivers, still to of no prevail.

My headphones are out of the question - tested them on another computer with the same in-game/master volume settings and they gave loud results (compared to my PC, which produced MUCH quieter volume).

I have a Razer Kraken 7.1 and tried a V2 version on my PC aswell = volume did not improve.

Any suggestion as to why this is occuring and how I can fix it? Thanks.

 

[JackMateo123]

I fixed it - uninstalled the latest window update of "Update for Microsoft Windows (KB4515384)."