ok the icon has now appeared. AC-3 DVD-Videos in Media Player is sending AC-3 to my av pre-amp. But when I play it with Media Centre I get no audio. It used to work, my guess is was using Power DVD mpeg decoder/audio features. M-Audio is set to Digital, FFDSHOW Audio set to SPDIF for AC-3 & DTS, and Nvidia purevideo decoder to SPDIF. bah looks like Purevideo is totally useless. Just used the microsoft tool to set powerdvd mpeg decoder as standard codec, and audio out via spdif works fine.