no audio capture for asus p7131d tv-tuner

hi
i own an asustek my-cinema p7131 dual tv-tuner. i'm running vista ultimate
x64 rc1 (on a second partition).
i'm using asustek drivers ver 13.3.1.4 for x64 (offered for winxp x64pro or
win2k3 server x64, but that's all there is). the drivers list in the device
manager as: "ASUSTeK Silicon BDA Video Capture" (the way it has under winxp
x64).

the video capture work as intended (finding a software that works under
vista was troublesome, but nevermind that).
BUT: the device doesn't play sounds!

i've narrowed it down to this:
1. under xp, the device/driver/windows itself installed a "713x BDA Analog
Audio Capture" that was listed in the "Sound and Audio Devices Properties"
from control panel (more specifically, in the record section, or the
volume->device section). i can find no such thing in vista control panel's
"Sound".
2. another difference i noticed is that under winxp, the device in device
manager has a "Properties" tag under which a "Europa audio capture device" is
listed for both "Audio Devices" and "Mixer Devices". the whole tag isn't
there under vista.

if you're willing, you can checkout some printscreens i've made of what's
described above at: http://rapidshare.de/files/36244658/BDAaudio.rar (118KB).

do you know what's the problem? can you think of a solution? i'll be very
grateful for any suggestion.