When I first installed the new ones it seemed to mess up my fallout 3 game. But I restalled them just now and everything seems to be working normally.
All the options in the Asus Xonar control panel are working for me.
You need to go into Windows sound control panel and right click on speaker then choose "show disabled devices" in order to see everything in the Xonar mixer controls.
It might also help to go into "Advance speaker settings" and set to 48000Hz DVD quality.
My control panel settings are shown for 5.1 dolby surround.