I have it through just the toslink, and haven't used it yet as it only outputs 2.1
I really didn't want to use HDMI as I was more than happy using the Toslink on my PS3 for DD 5.1 and DTS. Shame really as I hate having to have the receiver on just to use the TV's speakers, I tried using the mobo sound but my GPU disables it, might take a look on the bios though and see if I can get the audio through the mobo HDMI and the visual through the GPU.
Sorry for late reply, gonna go to bed in 10 mins too