🚀 go-pugleaf

Looking for help with PCChips M748MR motherboard on-board 4-channel sound 
card.
According to the manual, the line-in can serve as a rear output. To make the
switch it's necessary to use the AudioRack soft bundled with the motherboard.
When I activate the 4-speaker button in AudioRack, I do indeed see the rear
output control in AudioRack, but the volume is all the way down and the 
rear volume control is greyed out, so it's not possible to change the volume.
There is no rear channel sound. In the generic Windows volume control,
there is a 4-speaker control, but it's greyed out too.

This happens both in normal and HRTF mode and with all versions of drivers
I could find (the latest was dated around 5/99).

Has anybody had and solved this problem? My best guess is that either
the driver/application software is buggy, or there is a need to force
the 4-channel mode using a registry hack or something. 

PCChips didn't reply to my email, as expected.

Configuration: Windows 98, 64 ram, Celeron 300A.

Please reply to me directly.
Thanks in advance, Sergei