Your reference for "the absolute" sound?

Elastic. Temporal...Points in time. Memory and Age dependent, etc. There isn’t one, even at the individual level.

Your reference for "the absolute" sound?

Absolute? No such thing. Absolutely.

Great question as it's all too easy to get lost in a sea of subjectivity when it comes to audio playback.

One good way might to record friends or family talking. I found the quality from a digital camera to be surprisingly good but I'm pretty sure a decent smartphone would be good enough.

If the playback through your system convinces you that it's them then that's a good reference. I know it's an old Hi-Fi cliche but speech is a surprisingly good way to check accuracy, at least midrange accuracy.

As a bonus a simple home recording can also avoid innumerable recording effects such as compression, delay, reverb etc that are usually present in most commercial offerings.

I get the feeling that 'straight' recording is seen as  taboo by most recording studios.

Apparently it's not what we want.

I've been to over a hundred rock, ska, and jazz concerts but only a few classical live performances. For me the absolute sound is my stereo. I've never been to a concert that sounds as good as an excellent recording on my home system. I figured out many years ago that attempting to make my stereo reproduce the sound at a live venue was not my goal. Why would I want to make my stereo sound worse?

When you are sitting in front of live performers your brain filters out the bad acoustics of the venue and you mentally position the musicians in the sound stage. You look at the acoustic bass player and you can see him/her play every note. It sounds wonderful. But try closing your eyes for 30 seconds and concentrate on the overall sound. You will quickly determine that it really doesn't sound very good. It's diffuse, mushy, and full of distracting acoustic reflections. If your stereo sounded just like that you would say that the recording was terrible and the equipment was crap. The proof here is that virtually no recordings are made with a stereo pair of microphones in a single position. When we try to duplicate your listening experience by recording from the same location as your ears the sound is lousy.

The exception is live orchestral music in a venue with world class acoustics where you are seated in an ideal location. I've never had this experience but I accept that this is a live musical standard that is worthy of reproduction. However, it is very rare that classical orchestras are recorded with a binaural setup with no EQ and no processing. If this is the "ideal" for live sound then why do nearly all orchestral recordings use multiple microphones and sophisticated mixing routines. Apparently the "absolute sound" can readily be improved upon.

To address the OP's question regarding surround sound, going clear back to the Quadraphonic days it was mostly a gimmick to sell more speakers and more expensive multichannel gear. It was cool the first time you heard it but it became distracting pretty fast. The best modern multichannel recordings attempt to recreate the ambiance of a live venue or to locate musical information around you to create an interesting effect. The worst concert I ever attended was Emerson, Lake, and Palmer where they had four huge stacks of speakers set up in the four corners of the venue. Besides being oppressively loud there were constant effects of the instruments spinning around the room as if on a racetrack and it sounded like a musical joke. It's the only concert in my life where I got up and walked out in the middle of the performance. I couldn't take it any more.

When I worked in an audio business and the goal was accurate sound, but  I realized that for many consumers their basis for what they wanted their system to sound like was a jukebox.  It seems that times may have not changed much since then.