CMedia CMI8738 onboard soundchip

[crnholio]

hi list,
i have a msi kt4 ultra mainboard with an onboard CMedia soundchip. the sound sounds great, but my problem is, i can't listen to more than one output-channel. i've tried setting the sysctl commands as mentioned in the handbook:

>To set the number of virtual channels, there are two sysctl knobs which, if you are the root user, can be set like this:
># sysctl hw.snd.pcm0.vchans=4
># sysctl hw.snd.maxautovchans=4

here some more information on my system:

FreeBSD 4.8-STABLE
pcm0: <CMedia CMI8738> port 0xe400-0xe4ff irq 11 at device 12.0 on pci0

root at pimp:~>dmesg | grep "irq 11"
nvidia0: <RIVA TNT2> mem 0xda000000-0xdbffffff,0xde000000-0xdeffffff irq 11 at device 0.0 on pci1
pcm0: <CMedia CMI8738> port 0xe400-0xe4ff irq 11 at device 12.0 on pci0
uhci0: <VIA 83C572 USB controller> port 0xcc00-0xcc1f irq 11 at device 16.0 on pci0

might it be a conflict on irq 11?
i've also had some trouble getting freebsd freezed when trying some opengl apps.. but i assume that's related to the nvidia-drivers.

i would really appreciate some helpful answers on this one.
thanks in advance, 
espen