[SOLVED] Help with Home theater System

Hey all! My problem has nothing to do specifically with OSMC, rather it concerns the Raspberry Pi whihc is running OSMC, and Surround Sound. I tried asking on some home-theater forums, but the only answer I got was that it is too specific of a use-case to help.
Basically, in one line my problem can be reduced to “Help me get my surround sound system working, innit.”
My home theater system is a Sony DAV-TZ200, by now, it’s getting on in years.
It has one HDMI-out port, 3 video-in ports, which are of the jack type.
The ones we are interested in, are the two audio ports, labelled left and right, also of the jack type.
Of course, it has the 6 speaker connections, (it’s a 5.1 channel system), which are configured correctly, no problem there.
My question is, how do I get my Pi 3B, running OSMC, to output through this system?
I have movies having both AAC 5.1 and DD 5.1 audio streams.
And when I play them through OSMC, it seems to me as though it is playing in Stereo, all the speakers are playing the same sounds, but when I play it directly from the system, the experience improves substantially, it plays surround sound.
Also, I connect to my TV through HDMI from the Pi, and the HT system is also connected to the TV using the afore-mentioned HDMI port.
I read the wiki/forum page on getting surround sound working, but I felt my system doesn’t apply in any of the options there.
I came here because I figure there are other users who have configured their AVR/home theater system to work with their Pi.
Note : I am an intermediate noob, I can handle myself when it comes to Linux, and computer stuff, but I’m not like at a advanced, kernel-tinkering, package developing or something level yet.
I can post pictures of the back of the system, where the ports are, if needed.
Thank you!

Can you post a pic of the back of the DAV showing how everything is connected?

Actually, don’t worry. Just found a manual online…
There is no way to get 5.1 surround sound into the DAV as it only has a stereo audio input.
Your only option would be to use the Pro Logic Or Pro Logic II movie sound modes

Yes, that’s my conclusion too. That AV system it really designed to play back its own content, not to accept an audio input from another source.

Ah. Ok, thanks!
Will do that.