A-weighted means a-weighted filter. After you have get the DAC's SNR at different frequency, then use an a-weighted filter to calculate the SNR of the DAC. It makes the frequency which human is sensitive to be a larger value, which human is not sensitive to be a small value.
My english is not good, I hope you can understane.
Where can I get the A-weighted filter's spec or related documentation?
It seems that it is a standard filter, including the coefficient, or weighted number.