How you know your system is improving?

You have to know where the target is in order to hit it. Also the target must be real not just a pipe dream that can never be realistically achieved.

The problem of knowing what the target is goes back at least as far as Hume's argument that "taste" depends on educated critics who help the rest find the way.

Taste is a factor implied but completely secondary .😁

Anyway "taste" must be trained: ask a musician, an acoustician or an experimented audiophiles.

Because the target in optimization process is some specific balance between all acoustic factors and some ratio aimed toward a specific acoustic concept with the gear limitations used in a specific room ...

The main core concept is "timbre"...

After it is the "spatial characteristics of sound which information is encoded with the "timbre " perception phenomenon .....

After that "listener" envelopment factor and the source width auditory ratio are important to create...It is written as : LV /ASW in acoustics articles. There is almost no reviewer who spoke about that. guess why ? they sell a product they dont teach how to properly use it with acoustics nor they teach us how to optimize a product working toward his peak quality.

If you dont know these acoustics concepts and experience you dont know how to optimize your system/room and you will resolve the problem by the throwing of money i9n useless upgrades( half at least upgrades are completely useless in any audiophiles life ) And as a children in fron of a soup bowl unable to appreciate the cooking refinement you will say : "i dont like it , it is my taste " ...taste must be educated and trained...

it is not Hume we must consult here about"taste" but Helmholtz...

Then you are not even wrong here because "Taste" must be trained and play a role as gear marketing dudes and reviewers know very well and use this fact to attract us toward their product not toward knowledge in acoustics.They know how to frlatter the consumer in the right way, the way that suit them : expanse and expansive. They will never spoke about acoustics importance. They will sing the word "taste" in chorus.

«I love McIntosh amplifier as my mother soup because it is my Taste» -- Anonymous subjective deluded audiophiles 😋

«I hate McIntosh amplifier because they measured bad on my tool»Anonymus objective deluded audiophile 😎

I’m trying to follow, so is this what you said, basically? (I tried to rephrase it.)

"While personal preference plays a role, it’s ultimately secondary in optimizing an audio system. Developing a discerning ear takes practice – just ask any musician, acoustician, or experienced audiophile.

The key to optimization is achieving a specific balance between all acoustic factors within a room’s limitations and using your equipment to achieve a desired sonic concept. Timbre, the character and quality of a sound, is the cornerstone of this concept. Next comes the spatial information encoded within timbre, which creates the perception of a sound’s location and movement.

Following that, the listener’s sense of envelopment and the ratio of source width to auditory scene width (LV/ASW) are crucial for creating a realistic soundscape. Surprisingly, few reviewers discuss these factors. Why? Their focus is often on selling products, not on teaching proper acoustic integration and optimization for peak performance.

Without a grasp of these acoustic principles and experience, you might resort to throwing money at unnecessary upgrades. This approach, much like a child struggling with a complex dish, leads to the dismissive statement: "I don’t like it, it’s just not my taste." However, taste can be developed and refined.

Forget David Hume’s philosophy of taste; for audio optimization, we turn to Hermann von Helmholtz. By neglecting this crucial aspect, you miss the opportunity to truly appreciate the nuances of your system.

Marketers and reviewers exploit this lack of knowledge by emphasizing personal preference to push products instead of acoustic education. They cater to the consumer’s desire for grand, sweeping sound, all while ignoring the importance of acoustics. The word "taste" becomes their mantra."

Sometimes it’s the journey and not just the destination. 
As long as you’re being somewhat fiscally responsible, enjoy the ride.