Speakers position and listener position is only HALF of the story...Sorry...
And it is a common place fact in acoustic circle if not in audiophile thread....
And yes most people think the gear is the main important factor which is erroneous...
The passive material treatment and especially the mechanical acoustic control is the more important half...Why more important?
Because the first half is well known, the speaker/listener position; the other half is not even explained in audio threads : Room acoustic mechanical control with Helmholtz method about resonators and diffusers ....
And this part ONLY can compensate and can use for the better the specific difficult geometry, topology and acoustic material content of most small rooms ( carpet, fabric cloth pieces, furniture,books,mirror etc); the relation between speakers and listener position CANNOT solve by itself all these acoustic problems..
I never wrote a book but i was able to do my small room right... BUT It takes me 2 years non stop to figure it out , i am retired.... And now i know how to do the listening experiments and which devices can be useful ... And yes it is complex... But yes it may cost peanuts.... 😁😊
And it was the most fun experience in my life on par with cycling and walking and dreaming and reading....
Upgrading one piece of gear after the other is not audiophile experience, it is obsession maintained by ignorance of acoustic, sorry....