What VSTs would you recommend for improving audio quality of video calls?
Some general EQ'ing on the mic also works wonders for how well it sounds, but that's very specific to your voice and mic.
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Another use case of Equalizer APO where it is much better than everything else is compressing game audio. Some games simply have audio that was designed without regard for hearing safety (CS:GO is a strong contender for #1 here), and this helps immensely with it.