Forgive me if i’m wrong but is not Ben ( a member of this forum ) the designer of SONCOZ also the designer of the KTB ? Maybe he has some insights , this is technical beyond my skill set , so good luck with this curious investigation
However is not that far worse performance than this still is transparent when listening to actual music ?
I’m sure that when the root cause is identified some contrived test tone can be designed and it could be possible to hear this .
However pursuing perfection is never wrong , especially if it’s about implementation that only costs knowledge and not more expensive components.
ESS themselfs should have better documentation , that would benefit all products designed with thier chip set ?
There should be an ESS user group where people can help each other out .
And again thanks for the effort , this is the stuff that makes this forum great !