I've processed lots of sources with 5.1 audio that have "interesting" issues of various types. My favorite is when the LFE channel has a full range signal instead of a low pass filtered one. When that data is down mixed by what ever chip is doing it, there's way more data in the mix resulting in not what one would hope. These are studio provided sources that have been outsourced to 3rd parties for various reasons, but the LFE is often the red headed step child of audio data.

Idk why they have to make it so weird. My 2.1 setup just has the sub get the full signal and the built in filter takes care of it. Id been reading about how 'perfect' the atmos to stereo conversion is... what an odd issue to run into to throw a wrench in that(or just use it as a consumer). I guess theatres really need that LFE channel.

God, does 5.1 or better really shine on 90s surround sound movies. And occasionally newer ones, but a lot more back then.

They also hadn’t given up on original music. It’s crazy how much the soundtrack elevates otherwise-not-amazing films like Twister. I desperately wish they’d at least go back to caring about that.

We used to listen to a lot of music with Dolby ProLogic enabled even though the music clearly isn't encoded with that in mind. Since ProLogic works off of the audio phasing to decide what is sent to the rear speakers, a lot of the effects used in the music mix trigger ProLogic to send random things to the rear. It's an interesting experience. Maybe less so without the use herbal remedies too.??? Some of the call&response type lines from Beastie Boys would very clearly come from the rear, and was quite startling the first time hearing it. With 5.1 and beyond, everything is discrete tracks, so that trick no longer works. Do modern surround units even do ProLogic any more?