Digital output on M2N_E with logitech Z-5500

[polio]

hi everyone
when i plug my spdif dig out on my mobo to my z-5500 i cant get any sound. i think its the mobo for some reason. on the soundmax control panel there is no option to choose spdif out, all it shows me is the option to select 5.1 (with the black, orange, green mini jacks)

also in the 6 channel direct out, my center speaker volume is way down, compared to the others, but in movie effect its is loud so it seems to be getting a signal
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AMD64 X2 4200 SAM2, ASUS M2N-E, 4x1GB Transcend 800MHz, 2x Seagate 160GB SATA2 8MB 7200rpm, XFX 7600GT 256MB, LG 18X DVDR, Gigabyte Triton case, Zalman 450W PSU, BENQ 22in widescreen 5ms, Samsung 46" LCD Full HD, Philips Home theater

[Google]