QUOTE(DannyOP @ Jan 22 2016, 06:30 AM)
I'm using a Sharp 630x with native Netflix App built into its Android TV and optical out to Anthem Mrx 500 AV Receiver with 5.1 speakers.
Just hooked it up yesterday, able to watch 4k Netflix with Maxis 10Mbps, but how do you know which show is able to allow 5.1 ?
That's much better..

The DD 5.1 option is available for most Netflix shows or movies. Personally, I've seen or checked over a hundred movies & TV episodes & they all have the DD 5.1 option (works). For testing, you can use any of the Netflix originals like Marco Polo, Beasts of no nation, etc, as they'll definitely support surround sound. Firstly, is passthrough enabled within the TV settings? Also, some TVs have issues with passing through HD sound via optical out, so try using HDMI & the ARC feature. According to netflix, recommended Sharp TV models includes the UD27U, UE30U, UH30U & UC30U. Since you've reported getting full UHD picture on the 630x, then I guess it's supported, just not listed yet.
QUOTE
To adjust subtitles on most Blu-ray players, Smart TVs, and set-top boxes:
Launch the Netflix app.
Select the movie or TV show you want to play.
Select Audio & Subtitles from the options panel.
Select your preferred audio or subtitle options.
Press Back to return to the options panel.
Select Play.
Audio & Subtitles options are also accessible while a movie or TV show is playing:
Play a movie or TV show.
While the movie or TV show is playing, press the Down arrow.
Select Audio & Subtitles.
Select your preferred audio or subtitle options.
Note: If you are unable to complete the steps above, subtitles are not supported on your device.