Motherboard GA-890GPA-UD3H has a "SPDIF OUT". Whatever. What matters is that it is a digital output, so i connected it with a digital optical cable into the Logitech Z-5500 digital optical input and there is no sound... Feeling quite stupid, what did i miss? Does not the SPDIF OUT recognize an optical connection between the mobo and speakers? Perhaps the SPDIF OUT only works with coaxial cables?