[querty1000]

Anyone tested kodi 17 app on zidoo X9S (so without wrapper, so it play movies fluenttly?)

Kodi 17 is horrible in x9s when it is in a 5.1+ setup. Passthrough doesn't work (as querty1000 pointed out the android is heavily patched and not following standards). Even without passthrough, multi-channels AC3 doesn't work, DTS doesn't work and they play in stereo. AAC also stereo regardless of the channels.

My recommendation, do not bother. Zidoo should follow Xiaomi's example and follow standards. Maybe upgrade the box to Android 7.0 and start with vanilla OS. All they have to do is to to adjust their media player to the default passthrough in Android and stop messing with a fork. Such machine will be future proof because Kodi will never stopped to be developed.

But how is it in a non 5.1 setup where no 3d is rquired?

Then you can sell your Zidoo and buy a family pack of players that are better, a car and a house from the money you get back :-).
Zidoo is one of the rare players that do 4k *and* full frame 3D, if you don't need 3D you can use a Xiamo MI box or an Odroid C2 for cheaper money.