I have customers with DAC's that passed J-test with flying colors and still benefitted from low-jitter sources.
The current state of measurements is abysmal IMO. The state-of-the-art in reproduction electronics has left the measurements in the dust. No good correlation now. How many reviews in Stereophile have you read where the listener loves the component and JA measurements are crap? I can remember more than one.
Steve N.
Empirical Audio