Before we begin, I want to be clear.
I don’t want to get into semantics of formats vs upmixers and “that’s not real surround” etc etc. For the purposes of this thread, let’s just all agree that contextually speaking “Surround Sound” is going to be referring to sounds intentionally coming out of rear speakers. Agreed? Awesome. 
I recently got an AV receiver setup, and it supports Dolby Surround. In fact the product page here, indicates that by setting it to “DSUR” I am going to be enabling it’s use of Dolby Pro Logic I/II. Perfect, exactly what I need (based on my understanding)
https://helpguide.sony.net/ha/strdh79/v1/en/contents/TP0001605061.html
Now, I needed a game to test this on, and I read that Donkey Kong Country 2’s first level will output the boards creaking to the rear speakers. I tried throwing Rayman 2 on Dreamcast at this, and Ocarina of Time - but I couldn’t find any info on WHAT I was supposed to hear from the rear speaker. (Any info in this regard, a specific sound from a specific game, would be IMMENSELY helpful)
It’s my understanding that this old “Surround Sound”, being sent over Left/Right audio (Typically White/Red RCA cables) shouldn’t require anything past Stereo being set in RetroArch (Which I did find in an old thread to confirm)
For the LIFE of me though, I cannot get this to work.
I can get Windows sound test to output test sounds on all 5.1 individual speakers and the subwoofer. I can toggle between 5.1 and Dolby Atmos in Windows, but neither has made a difference in the end result.
What am I missing?
Can anyone tell me a game with a confirmed Surround Sound sound effect, and/or music, in the early moments so that I can test more comprehensively?
Is there a setting I am not considering in RetroArch?
Any information/help in this regard would be amazing, as I am not finding anything really in these forums or online that is pointing me further in the right direction to getting this to work.