5.1 passthrough TV is more dependant on your TV then the HDMI device.



I had only one TV that could pass double digital 5.1, nothing more or you get mute sound.



That's the same problem why you can't get 5.1 audio from a Chromecast via passthrough, Netflix and others use double digital + for 5.1 audio, that is destroyed on passthrough, you can only get 5.1 on Chromecast connecting it directly to a compatible receiver.



That why most people are having 5.1 problems over here with mibox.



I faced this problems for years building my own htpcs, and only have success with a Sony tv, downsampling all audio to simple double digital, (ac3), DTS, DTSHd and others formats are impossible to get without a receiver with HDMI input