[freebo86]

So I have a Vizio SB3651 5.1 soundbar - center bar, sub and two rear satellite speakers. My android box is the AFTV2 running Kodi 17.6.

The AFTV2 is connected to the TV using HDMI, from TV down to the soundbar is Optical (I tried to use HDMI-ARC from TV to Soundbar but same results). Basically when I watch something I have audio delay not sure what the issue is here or what is going on.
Sharp Digital Audio Output is set to RAW (which is the same as bitstream).

The Soundbar supports the following; 

• Sound Enhancement TechnologyDolby Digital®, DTS Studio Sound™, DTS TruSurround™, DTS TruVolume™, DTS Digital Surround™
  

In Kodi, I enabled Audio passthrough with all 3 options enabled below it.

If I disable Audio passthrough clearly i do not get 5.1 sound from the soundbar unless the source is true 5.1. Am I correct in assuming this?

I guess what am I doing wrong here is it my settings? Am I not understanding something correctly on when and how the audio passthrough should be enabled?

[DaVu]

One explanation might be, that the TV does something with the audio stream before it outputs it to the soundbar. The video stream is directly shown on the TV. So there might be some delay. If possible, I would try to connect the AFTV directly to the soundbar (assumes that the soundbar has HDMI in and outputs) and then connect the output of the soundbar to the input of the TV

Then enable passthrough in Kodi and all is fine.

If you use it like this:

AFTV -> HDMI -> TV -> optical -> soundbar

and disable passthrough, then you won´t get 5.1 even if the source is 5.1 because optical is only capable of 2 channels

if you use:

AFTV -> HDMI -> TV -> HDMI -> soundbar

and disable passthrough, you will get 5.1 PCM at the soundbar, where you won´t hear any difference to passthrough. HDMI is capable of 8 channels.

Another recommandation would be, to disable passthrough, enable "Sync Playback to display" (which should avoid the delay) and use HDMI everywhere you might be able to.

[freebo86]

Thanks for your prompt response! 

So the soundbar does have HDMI In. 

The reasoning I didn't go from AFTV to Soundbar using HDMI as the Soundbar will not pass through 4k content.

Your second option of doing
AFTV -> HDMI -> TV -> HDMI -> soundbar

If I play a SD content that does not produce 5.1 I won't get that output and my rear satellite speakers won't do anything. Do I not need to enable pass through in order to get the 5.1 output at the soundbar even when playing content that isn't 5.1?