I've just recently connected my UN55MU630D to an analog audio unit, through a toslink cable into a digital to analog conveter.
The audio settings are set to Autio Out/Optical, and the expert settings are set to PCM for both HDMI Input Audio Format and Digital Output Audio Format.
The bizarre thing is that I can hear all the tv sound effects through the system (when you push the home button, or move left and right across apps), and the Pandora app works without any issues, but nothing else works. I've tried Netflix, Amazon, Disney, YouTube and our DVD player, but there is no sound coming out the speakers. Sometimes I hear an audio glitch, as though it's trying to connect to the speakers and play something, but nothing comes out. And sometimes the Netflix start up sound works, but then nothing in the app does.