most accurate loudspeakers....

In my opinion the goal is to recreate as closely as possible the illusion of a live performance, and this implies taking psychoacoustics into account. Just because something can be easily measured doesn't mean it's relevant. If low-order harmonic distortion is inaudible, then an impressive-looking measurement in that area is irrevelant.

To give a more common example, as long as we measure the on-axis anechoic response but listen to the power response, there will be a disconnect between frequency response measurements and subjective perception.

Following this line of thought, the most accurate loudspeaker is the one that comes the closest to reproducing the perception of a live performance. We don't presently have a metric that accurately predicts subjective preference - indeed, the audio industry has thus far resisted the adoption of such a metric presumably because there would be far more losers than winners among manufacturers. What we'd need is a psychoacoustically-weighted metric that takes into account the relative audible significance of everything the device does to the signal (the "transfer function).

Of course I have my opinion as to which characteristics are likely to result in a speaker that closely approximates the perception of a live performance, and frankly some of these characteristics are unlikely to show up in published measurements. Among these obscure characteristics that I think matter are dynamic linearity (lack of power compression or at least uniform power compression across the frequency range) and radiation pattern smoothness (related to but not the same thing as power response).

I don't know of any speaker that really "does it all", but my personal leanings are generally towards planars and horns rather than direct-radiator dynamics - even though the latter are more likely to produce impressive-looking conventional measurements.

Duke
dealer/manufacturer

Reference 3A is the most pure by far ,if you know what a real instrument sounds like then one listen and you
will know. The critical Midwoofer driver is completely made by hand in house the tweeter is far better then the stock ring radiators out there If your electronics are not bleached out like Naim for instance than go out of your way
to locate a dealer .

no speaker is accurate, period. most speakers state their frequency response within 3 db. that is not accurate.

at best one can a speaker is less inaccurate than another.

a speaker is either accurate or it isn't. it can't be incredibly accurate. it can't be slight;ly accurate. it is not accurate and not perfect.

there is no way to assess a speaker's accuracy. there does not exist a definition of accurate nor a way to objectively measure or calculate an inaccuracy score.

since we are expressing opinions, i would say the quad 57 is the least inaccurate of all speakers, within its range.

the thiel speakers sound top heavy, i.e., peaky in the upper midrange/lower treble.

Most of the producers and big studios use ATC while they record and mix. For home use I believe they are toooooooo flat. No salt, no sugar, no spice. Simply flat. But professionals like ATC because they give them confidence for the final product. For ex. Pink Floyd used ATC for all their recordings and band members use ATC in their homes.

I would vote for any speaker that:

(1) Has ruler-flat frequency response, at all power levels;
(2) Is completely phase coherent, at all frequencies and at all power levels;
(3) Has a completely resistive load at all frequencies, in order to present an entirely benign load to any amplifier;
(4) Has very high sensitivity, so "detail" is not lost at low SPLs;
(5) Does not interact with the room.

Trouble is, this is impossible with current technologies. Closest you'll find is an actively biamplified line array with a DEQX.