How can you say it is "superb" for directional accuracy, when the DAC is basically a stereo DAC with DTS Headphone processing added on top.
There is NO way the GameDAC can have any idea if the sound in a game is coming from front or back , up or down. Only left or right, when the soundcard (GameDAC) is stereo only.
No amount of echo , reverb or phase manipulation on top of the Stereo signal will recreate that positional info.
Now, if the GameDAC was actually a 5.1 or 7.1 soundcard, that took discrete multichannel input from Windows (and from games), it could actually process/virtualize that multichannel positional information into a stereo headphone properly.
But as it is not, it's just a glorified stereo effects engine.
Not up there with the best of Creative, Sennheiser or even Asus sound cards in true 3D positional headphone cues.