I am not an audio scientist nor expert. I do not think to be either an audiophile.
I do not understand curves in the graphics.
In personal experience, with a DAC based on AK4399 and other AKM op-amps, I heard something I cannot explain better than a warm, smooth presentation, instead o a detailed, clinic one, that could be the result of the implementation.
However, it is the same AKM that talks about velvet sound:
https://www.akm.com/akm/en/product/datasheet1/?partno=AK4490EQ
https://www.akm.com/akm/en/product/featured/velvetsound/
And there are comments from people like:
https://www.superbestaudiofriends.org/index.php?threads/akms-velvet-sound.2356/
You can say that there is no hard evidence but, perhaps, there can be something more in the listening.
Or it is completely wrong?
Good measurement figures are exactly good listening?
Or, put in another way, same figures for two devices mean that they sound the same way?