MacBook Air 2017 – Mini DisplayPort to HDMI surround sound problem

OK, I think I cracked it. I didn't realize that the soundbar emulates surround sound, but physically it's not 5.1.

So: MacBook shows 5.1 because it's able to send 6 channels. But when it comes to soundbar, it changes to 2 channels. Soundbar decodes Dolby Digital and then emulates surround sound. I hope I understood it well.

Conclusion: both MacBook Air 2017 and the HAMA adapter support surround sound. But finally I chose Mi Box S for streaming. I think the picture is more stable. HBO GO is much better watched on app than on internet browser. Maybe streaming services should develop apps like Apple TV.

The topic can be closed or deleted. Or maybe somebody find this helpful.

Update: I accidentally found and turned on an option "Prefer AC3 Passthrough" in audio tracks in Apple TV (why is it there and why is it not default?). Now the indicator on soundbar shows Dolby Digital, but on TV screen is still "stereo". In MIDI configuration it automatically changes to "coded digital audio" and HDMI shows 2 outs instead of 6.

Does it now play 5.1 or not?

Or maybe it's better to buy Xiaomi Mi Box S for Apple TV, HBO GO etc. instead of this adapter?