5.1 Audio Output on (late) 2016 MacBook Pro

I've just started using my new (late) 2016 MacBook Pro.

Today I bought the Apple USB-C Digital AV-multiadapter, hoping to output both HD video, and 5.1 sound from my Mac.

I had no trouble connecting the Mac, and got both audio and picture with no problems at all.

But to my disappointment, it seems like my new Mac is unable to output more than 2 channels os audio via the AV-multiadapter.

The Mac is currently connected to my LG Surround Receiver, like every other HDMI unit I have.

I've checked my Audio MIDI setup settings, and was only able to find 2 channels of audio.

I was a bit surprised to see my audio output as DisplayPort; not HDMI.

Is this the case with the new MacBook Pro, or is this a matter of settings?
I couldn't manage to find any information anywhere, so hopefully the community can come up with the answer.

This is how my Audio Midi Setup looks. (Pardon the Norwegian...)