Where do you see 5.1? Are you talking about the S590? It's gonna output what's on disk, be it 2.0, 5.1, or 7.1, or 116.9.

From the Amazon description:

Sound you can feel
Experience the highest sound quality with Dolby TrueHD and dts-HD codecs which reproduce high-definition sound with 7.1 channels of discrete audio for uncompromised quality.8

I am the Doctor, and THIS... is my SPOON!