@James-F there is no analog circuitry or load before PCM1862 audio ADC except a 100K pull-down to prevent floating.
@BuckoA51 so the mono output was no better? That somewhat contradicts with esp’s post, although in that case signal was tapped before buffer and op-amp. Is there some particular game where distortion is most apparent? The modified VA1 here should sound close to your VA5 but I have hard time hearing any notable distortion after pre-amp gain fix (Sample 4).