Analog Devices AD1981A @ Intel 82801DB ICH4 - AC'97 Audio Controller is the full name of the controller (which is onboard) as per Everest (one of your favourites, right?
). The actual mobo is Intel D845GRG (haven't checked Everest details), but the chipset for audio is as above.
I did forget to mention in my post that I did attempt to load the XP driver downloaded from Intel's audio support for this board since there was no Vista driver available, and it installed fine, but the same problem happens.
I have even changed the mobo for an exact replica but the same problems occur. Naturally, sound works in XP for both boards anyway.
Remember, this problem is not the same as others where the device is not installed/started correctly; the audio driver
is installed/started/working as far as device manager will say, and of course is interacting with the microphone correctly. Hmmn, just had a thought that the chipset drivers for the Intel board might be causing an issue... considering the mixer shows sound being played through the device, but nothing on the output... perhaps it's being lost through the southbridge...
I might try the XP drivers for the chipset if I can find them.
Have you heard of this problem before (where the driver is actually working as expected and no "unknown devices" or unstarted devices in device manager?