I'am using the latest 1764's which looks to be the same one showing for the Xonar DX2 and the Xonar D2 which is
Beta Version 6.12.8.1764. This worked best for me with Windows 7.
But to get
all the mixer functions to show up in the Asus recording mixer I had to go into the Windows sound control panel and then to recording options then set it to
show disabled devices and
show disconnected devices before all the sound mixing options would show up in the Asus recording mixer UI.
You don't need to mess with the speaker test in Windows, just leave that one set to
stereo, otherwise the surround won't work right.
Here is how the mixer panel will look with all mixing enabled.
And the next one shows the settings for using the 5.1 analog for standard computer speakers.
I can also tell you which ones to plug into if you have standard logitech computer speakers. The colors don't match up at all.
For digital out through the spdif you just use the dolby digital setting instead of PCM.
I included snips of the windows sound panel showing how it looks when you get all mixing functions enabled so they show up in the Asus panel.