Well, I don't have optical input on my speakerset. And my speakers only support 3.5mm audio jacks. If you know something which can change them into another jack I think other stuff could be used.
Btw, I am talking about the Black, Orange and green cables. Can't really use the stuff which goes into my subwoofer since the ones going into my subwoofer are only the ones for FL, BL, BR and C.
EDIT: Is it possible to have the output of my PS3 (optical out) go into a soundcard so that it goes out of my speakers? If so, do you know a sound card which supports this?