There are some DACs such as the Weiss DAC2/Minerva and the DAC202 that can analyze the signal coming from the DAC to determine if your set-up is bit perfect. This is done by using a sound file provided by Weiss. The DAC software has a reference file of the sound file that you'd provide from your computer, and can compare your computer's output to that file to determine if you have achieved bit-perfect output.