This is very timely...

I want to add that extremely flat frequency response and extremely low distortions don't have correlation to the real listening. The religious belief in measurements shows the incompetence of the author.

If audio writers who praise these products asked mainstream speaker designers why they don’t make super-efficient speakers, they’d learn that with efficiency comes compromises—in frequency-response linearity, dispersion, distortion, and power handling. Few highly efficient speakers achieve a respectably flat frequency response and broad dispersion. And many of the primitive tube amps that are typically used to drive them have very high output impedance, which will interact with a speaker’s impedance to change the sound in ways the speaker’s designer didn’t anticipate and likely wouldn’t condone.

This author doesn’t have idea what does he talk about. His technical knowledge is zero. High efficient speakers don’t have the thermal distortions. These distortions cause compression, significant frequency response changes on different loudness. High efficient speakers don’t need power more then a single watt.
SET amplifiers has the lowest distortion on low power (first watt). SET have the lowest distortions, no high order distortions and transistors thermal distortions.
Bottom line, a proper built highly efficient speakers with SET amplifier system sound most close to the real classical or jazz music performance.