Audio setting for my soundbar (LG SK5)

I have a new 2.1 sound bar (LG SK5) which is connected in the following way:
Android Box (Amlogic S905 beelink mini mxiii) --> Sound bar (through HDMI cable).

On kodi audio setting I have output options: aml-m8audio PCM, aml-m8audio HDMI.
Should I set to HDMI?

Also, the sound bar supports Dolby Digital, DTS and LPCM.
However, I dont know if it supports multi channel LPCM or only 2.0 channels. How can i check this? there is no visual indication on the soundbar.

Therefore I dont know which setting to set:

  1. 2.0\2.1\5.1\7.1 channels? Does it matter?
    2.passthrough to DTS and DD and transcoding to AC3 or no passthrough, and let the Android box to do the work?

Hope you can help,