yo gz,

yesterday i built a home theater pc. everything is working fine apart from 5.1 audio.

heres my setup:
46" 1080p bravia
pioneer amp (i dont know the model number right now but i can go and check if its necessary)
pentium dual core e5200
asus p5ql-pro motherboard + spdif/optical pci adaptor
ati 4350 hdmi gfx
happauge wintv nova t 500 dual freeview tuner
lg bluray drive
1tb hdd

now, I am using the hdmi out on the graphics card for video, which at the moment also seems to be putting out stereo audio to the amp, but has no option to use 5.1

i bought this from playtech so i could use an optical audio cable:

it picks up that there is a seperate digital output, but when I hit "test" in the sound settings, I can't hear it.
it outputs stereo audio over the hdmi cable, so to see if that was interfering i used a dvi->hdmi converter so the card was only displaying the video, but still, i could not hear anything from the optical

so, i was wondering what i should do now.

is there some kind of cable that can go from the several regular stereo ports on the back of the mobo to an optical out

or is there a way to use the optical thing i bought

or do i need to buy a soundcard (be it usb or pci)

or is my amp ruining everything

thanks :)