Disable all options in the DSP Studio.
Reduce the playback device's buffer size to its minimum.
If you're using ASIO, reduce the latency/buffer size in the device's ASIO Control Panel.
Set live playback latency to the minimum size.
Beyond that, I'm not sure that there's anything you can do to further reduce latency.
If you're sending HDMI out from the PC to a television and using the built-in speakers, I don't believe it will be possible to have accurate lip-sync at all.
The display expects that audio and video are being sent in sync and will be adding a delay the audio to sync it up - which would normally be a good thing, but not in this case.
If the HDMI signal is being sent to an external device like a receiver, it's possible that you would not have this automatic sync correction being applied, which would allow you to sync things up.
Most televisions have a minimum of 20ms latency, and you should be able to get the total WDM driver latency below that.