I think it's just the built-in Windows thing, Sonic or something.
It helped a bit, thanks :)
By virtualization do you mean stereo, 5.1, 7.1 and the like? If so, I'm using 7.1. I'm not very experienced on this kinda stuff.
I installed Equalizer APO + HeSuVi, and it works now in PUBG and otherwise. The only downside is that the overall sound volume is too low in general, even with sound maxed, headset sound maxed, and in-game sound maxed. It also seems the Realtek HD Audio Manager is missing its equalizer/sound effects and option to uncheck the "loudness normalizer" or whatever it was called. Please help me.