I have installed the Xonar as 2nd soundcard. For Simvibe and connecting my 5 Butt Kicker I need 2 sound cards. To disable the Realtek onboard sound chip, so no option for me has been. This scenario with multiple sound cards can not be realized with the Asus drivers. The driver installation aborts with the message that there is no sound card is found (although it appears in the device manager).
Google goodness I came across UNi Xonar, an alternate driver implementation, which packages the significantly more current driver of the chipset manufacturer plus the ASUS and CMedia tools.
UNI Xonar driver to work properly, and I am happy.