There is no, and I mean NO examples of anything demonstrated to be audible which is not also easily measurable.
I agree on spec's. But why does each DAC model sounds different? Does the designers not measure? Lowlevel signals below the tresshold of measuring equipment which itself also suffers with distortions due electronic components and LCR properties. It is also very hard measuring signal behaviour in a dac playing music. Static measurements are just a part of the story.