It is the LG 65UB9300.
They are all set from the factory to PCM only. However. All these sets can pass Dolby Digital as well. It just needs to be enabled in the service menu. PCM to AC3. Then another change has to be made in the service menu. The new AC3 setting. It has to be written to all 4 HDMI ports. I know many many owners have complained about these tv's only passing PCM. And I know other brands. While very few. Can pass it as well when its factory enabled. Some what of a holy grail when you get a tv that can actually do it. These are my notes from a previous post. But, I wanted to make an official thread to get this word out for LG owners out there with 4k sets.
Just an update. I followed through with LG allowing the tv to pass Dolby Digital. Not just PCM. It can be done on all 4k LG tv's. It is simply disabled from the factory in the service menu for LG does not have to pay Dolby Digital licensing fees. That is my guess. Or people simply do not care enough and LG leaves it disabled because of that. I am using HDMI ARC with my LG soundbar as well. Picture attached for proof. My soundbar also confirms Dolby Digital is being used. So, everyone saying these tv's are just limited to PCM and will only pass that. Using HDMI or Optical. It is completely false and needs to be addressed in the service menu. LG will do this for you for free as long as the tv is under warranty. The tech just left the house a few minutes ago.
I also wanted to add. Since the tech. here had direct access to LG techs. These guys even have access to the actual television models while working on the phone with them as they go. I asked if a firmware update would revert the previous settings back. He said absolutely not and they stick when making changes like that in the service menu. I would also suggest not doing something like this yourself. One false move in the service menu and you will have a big expensive brick. Call LG instead and they will be happy to get this set up for you and have someone come out.
Link to OP with picture. http://www.avsforum.com/forum/166-lcd-flat-panel-displays/1973841-2014-2015-lg-4k-owners-tv-can-pass-dolby-digital-hdmi-arc-optical.html I don't know how to post the picture on here.