[Etzi]

Are you sure you test a version that worked formerly? Sounds like something Analog is plugged into the TV :-) Headphones?

It was that "not so shity AC3 448Kbit/s" build, then suddenly I noticed (decided to actually watch movie, not only test audio) audio sync issues which I could not fix, so I decided to reinstall from scratch.
Currently works fine, after I fixed "human error" with settings.
I cannot plug headphones to it, it is on the wall, so only headphones which can be "plugged in" are BT ones, another option is plug them into receiver.

Also, got confirmation from other user (via PM) with Sony TV with same chipset, that this build works fine (no sync problems), hence why I started to suspect my installation.
Also I checked Jenkins to see actual changes in this build and there were none, except that AC3 bitrate change as you said later.

So currently running: kodi-20170117-13f39e2-shitty-armeabi-v7a and after complete clean re-install there are no sync issues or other audio issues.
(Except of course issues and limitations of this MTK chipset itself, which you obviously cannot fix, only workaround with AC3 bitrate change.)