Hi! I've installed Home Premium x64 just yesterday and I needed the same driver.
After a few incorrect downloads and frustrated bad installations I've found the following driver:
ftp://ftp.asus.com/pub/ASUS/misc/aud...6320_Vista.zip
If you try to install it by running AsusSetup.exe, you'll get an error message telling that your hardware is not connected or something like that.
But you still can install it by the old ways, directly on Device Manager, telling Windows where you have uncompressed it.
It rocks! See the screenshot below:
There is a new function named Sonic Focus. Man, what an amazing boost it gives for your high and low frequencies. My Edifier e3100 never sounded better!!
Games, movies, music, incredible crystal clear sound.
I only have stereo (2.0), but the settings up to 7.1 are there as well.
Sorry for my english. I'm Brazilian
Good luck! enjoy it!