For 2 years 7day/7 without a day without doing acoustic experiments because i am retired i learned :
it may cost nothing to fix your system/room.
It ask for a great amount of listening experimenting time.
Generally the most expanse on upgrades someone do the less he understand acoustics.It is easy to verify this rule reading threads.
All room need acoustics controls (not just passive treatment) why ?
Because the room is linked to a system as a system is linked to the room, but the sound quality pertain to neither of them... Why?
Because save if you invest a fortune creating an acoustic architectural optimal design for every ears, the sound quality depend ,not so much on the room ,the gear system, but mainly in your hearing specific characteristics and training abilities to CONTROL the system room to your liking...
i designed 2 dedicated acoustic rooms with "scrap" materials on hand...
I even created "a mechanical equalizer" using set of "specifically" distributed Helmholtz resonators...
the sound quality was astounding for the price paid for my gear and holographic immersive with some recording so well made it was as if i was with the musicians...
Acoustics rule audio....
No branded gear name but acoustics....
Give me anything i will made it "relatively" good....Acoustics rule...
I must add that i improve all my headphones too. as i did with my gear with resonance controls.
An optimally controlled low cost system in a controlled room designed for it will be better in my book than almost anything pricier out of the box in a living room .( it is a general rule. I dont claim that a 1000 bucks system beat a 100000 bucks one, use common sense. )