Mac Mini Stereo signal?

I currently have a mac mini (mid 2011) hooked up to my yamaha receiver via the optical output. Prologic, Dolby digital and dts work great. However I prefer to listen to my music in 2 channel stereo. When I but my yamaha to stereo it still shows the PCM connection but there is no sound. Is it possible to get a true stereo output form the optical port?