Speakers exist optimally and really in room which are tuned by one owner for his own ears...Otherwise it is only a well measured abstract design because not living yet in a room and  not yet working for some ears...😊

 

I tuned my room by ears with one hundred Helmoltz resonators... It takes me one year of incremental tuning process...The results was not perfect at all in term of flat frequencies response  just totally astounding FOR ME.... 😊

 

A flat frequency response made some sense between two pieces of gear as a dac and an amplifier for exemple ...

But electronic engineering is not acoustic...Here frequencies responses ask for a more deep investigation ...

The answer from acoustic and psycho-acoustic is more complex and way more nuanced because here we introduce the specific ears coupled to a specific brain in a specific small room ...

 

 

 

Here an article by an acousticuian who teach studio acoustic ( the underlining is mine )  :

 

«The Hunt For Your Prefered Tonal Balance

First, as you are shaping your music, you’ll automatically gravitate towards a tonal (frequency) balance that resembles your own personal taste.

Some people generally prefer more bass, some less. Some like more present highs and “forward” mids, some prefer a “neutral” representation.

If you’ve ever applied EQ to a speaker system for a client for tonal shaping purposes, you’ll know that a balance they like can be drastically different from what you like.

The point is that you have developed your very own preferred subjective frequency balance through years of listening to your favourite music on various speakers and headphones, at different volumes, throughout different periods of your life, etc.

That subjective frequency balance is personal to you, and you alone.

That’s why acoustician Bob Hodas says:

“I have yet to find an engineer or studio owner who actually wanted a “flat” room. Experience shows that a flat room has no personality and is no fun to work in. Equally important, working in a flat room does not necessarily ensure a recording that sounds good elsewhere.” – Source

The problem is that if the frequency response of your system does not mirror your personal taste, you’ll constantly be over-compensating for it.

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Getting To The Promised Land of the “Flat Frequency Response”

Of course, no matter how good you become at referencing and keeping your taste in line, it will not compensate for a serious lack of information. You cannot judge what you cannot hear. If the frequency response at your listening position is simply too crooked to start off with, no skill in the world can make up for it.

That’s why the basic requirement for your home studio is this:

Your frequency response should be balanced to match your taste, and nothing should be drastically missing.

Once you’ve got that, you’re good to go. The rest is up to you and navigating the choppy waters of “taste drift”. Interestingly, looking at the big picture, your room’s frequency response suddenly becomes a non-issue.

You’ll then realize that the really important acoustic aspects of your room are less about frequency, and much more about time.

Because the way that reflections mess with your perception of the sound stage and dynamics, and the way that resonances and excessive reverb cause masking, is not something you can cure with skill and technique.

“Contrary to popular belief the big problem with bass in hifi is not lumpy bass, standing waves, room modes, hot spots and suckouts. The big problem is sound masking.” – Art Noxon

And solving those issues, more than anything, will help you get what you want. A sound that you can trust, a sound that lets you reliably make decisions, one mix after the other.

Sure, you won’t be able to say: “My room is perfectly flat”, but then why would you want that anyway.

Instead you’ll be able to say: “I know and trust my room. I can hear every little detail. And I know that the decisions I make translate perfectly and exactly how I expect them to.”»

From :

https://www.acousticsinsider.com/blog/flat-frequency-response