All Class-D’s today have the same problem. The switching frequency is too low to be filtered out effectively completely with the Class-D’s output filter, without effecting the upper mids and highs.
A statement George loves to repeat without practical data to back it up with.
He’s the guy who in the 21st century argues airplanes can’t fly because they are heavier than air.
Me, I'm loving Class D right now.
Best,
E