Continue from the previous post about PCM56P-J here, I should admit that chasing the highest grade for this DAC IC is just like playing a fun game. Early disclaimer for this grading is actually made and measured by the Burr-brown manufacture to differentiate the measurement result after the IC's come out from the production lines. The closest to the best THD specification will be stamped by "K", the lesser THD number will be the "J" stamped and the last is no grade. Fun fact about this THD number can also be optimized, depends on the application use. Other than that, as stated in the datasheet, most of this R2R DAC IC's made by Burr-brown can be do the MSB adjust, so the THD number can be much better after this adjustment.
So, what this grades marking are for? Is it only for marketing purpose? Well, short answer it is not. Without or with MSB adjust, the final THD number can be better if the original IC having advantage from the lowest THD number. Other than that, the reason for this grading is because the MSB adjust taking another process in audio manufacture which require more time and measurement. So out of the box, Burr-brown R2R DAC IC using grades to determined THD performance without any MSB adjust. This is become more easy for the audio manufacture put their product based on the specification requirement.