I'm trying to get full 5.1 surround out of my 2009 Quad 2.93 Mac Pro when playing games in 64-bit Vista. I want to send the multichannel audio from e.g. Left 4 Dead over optical TOSLINK to my Logitech Z-5500 speakers. Currently when I try this the computer only outputs stereo sound. I haven't encountered any definitive answers on how to get real time surround to work, but I have found the following information. The onboard sound chip is some sort of Realtek HD Audio. I don't know exactly which chipset. The Z-5500 is capable of decoding DTS 5.1 and Dolby Digital 5.1 input streams over the optical cable. This works fine for movies which are already encoded, but apparently to get games to work in surround I need either Dolby Digital Live or DTS Connect to encode the audio from the game in real time. However, I haven't seen any way to enable this in the Realtek HD Audio Manager (Boot Camp driver) or the Windows sound control panel. Is the 2009 Mac Pro's motherboard compatible with Dolby Digital Live or DTS connect in Vista x64 on Boot Camp? If so, how do I enable it? If it's not, can I bypass the problem anyway using third party drivers or plugins?