Who said “ flat freq response “ is the best?

@ieales : 

The market has just not responded that well to it. While Vandersteen and Thiel have ardent followers they also have not dominated the high end speaker market. Neither have single driver designs. 

Best,

E

@kalali 

06-24-2018 12:41pm

This discussion begs this question: would two different speakers with identical frequency response curves sound the same in your room? I'm betting the answer is no.

There are so many other variables. Impulse response, compression, dispersion (power response)  and distortion among a few of them. 

ESL's have often really mediocre FR but their lack of reflections make up for it in detail and imaging. 

Going back to something @elizabeth pointed out:

The quality of treble is often a function of room acoustics. Try throwing pillows and blankets on the floor between and behind the speakers as an experiment. You may be awesomely surprised at how much this enhances sound, despite the first reflection mantras dominating the topic of room acoustics. 

Best,

E

So much to chime in on:

Loudness curves - Yes, this makes it important to listen to a speaker at your normal listening volumes, or get one that is flat and use a loudness compensation like Yamaha has or Dennon used to. A speaker tuned for 65 dB listening is going to have more bass and more treble than one designed for 90 dB. Some of the Dynaudio speakers are great examples of this.

Imaging - Wilson, among others, has taken advantage of using a dip at 2.4kHz or so which gives a perception of enhanced imaging, at the loss of some information. Not all wilsons, this seems to have fallen out of favor recently.

Detail - By using a ragged frequency response some speakers can appear to enhanced detail. B&W 802D and GE Triton 5 have done this, and bowled JA over. I can’t stand them, but I am not buying your speakers.

The GE Triton 1 offered a nasty sounding AMT with a very exaggerated upper octave. To me that was painful, but apparently older listeners love them.

My last point is, your hearing is unique and changes over time, so regardless of a technical ideal, or a particular reviewer's take, you need to buy speakers that are ideal for you. If you know you have hearing deficiencies in certain frequencies, maybe that is something you should look for when buying, speakers which naturally have more in that area. Nothing wrong with that. :)