Just got a Playbar and knew ahead of time about the 5.1 Passthrough issues, so I bought a Monoprice 4x1 HDMI Switch (7974) that has been mentioned here. I have an LG 65UB9500 (2014 model), and I'm having a few issues.
When I run Toslink from the TV to the Playbar it works great. I get 5.1 from Netflix (smartv), and I am able to control the Playbar volume through the LG Magic Remote. GREAT!
When I run the setup (PS3, Popcorn Hour) through the 4x1 switch, HDMI ARC between the TV and switch, and Toslink from the switch to Playbar, I have problems. I get sound from the Playbar, but am no longer able to control the volume and the TV's speaker auto ONs and I am not able to select External Speaker (HDMI ARC/Optical) as it automatically selects back to TV Speaker.
I have the 4x1 dip switches set to Up, Up, Down, and audit works, but not being able to use the 4x1 switch to get 5.1 audio is frustrating me to no end.