Looking for the next level in imaging...

I agree that a lot of studio recordings are two dimensional. The images sound great but they all line up in one plane. There are exceptions like that Blue Turk, that I mentioned- really good recording from the early 1970s. Cowboy Junkies‘ Trinity Session was recorded with a stereo mic in a Church. It has a great spacious soundstage that sounds fantastic on modest and grand stereo systems.

I stream a lot of music on Qobuz now.  The music produced by the big name studios has much better dynamics and 3D soundstage vs. a lot of these lessor known studios.  Voices will move to the left or right and then back to center on some songs by less well known bands.  But I still love all the music, the large selection on Qobuz.  A number of gems to be found.

I appreciate live recordings more with my current speakers. The large spacious soundstage of live recordings come across as interesting and enjoyable.

@polkalover  The most difficult aspect of audio system performance is imaging. There have been many articles written on the subject. Relatively few audiophiles have heard a system image at the state of the art. Most systems can image well to a point, about 90%. It is that last 10% that is difficult to achieve. @mikelavigne made some great suggestions, limiting the number of crossover points and room symmetry are very important. The speakers have to see identical, but mirror image environments. I would also like to add a few points and suggestions. Early and even some late reflections can ruin imaging. There are three ways to optimize limiting reflections, sitting closer to the speakers has it's limits, choosing speakers with controlled dispersion and finally acoustic treatments of the room. Horns and ESLs are examples of speakers with controlled dispersion. ESLs can be formatted as full frequency line sources which IMHO is the speaker type with the best radiation pattern of all. They send virtually no sound to the side walls, ceiling or floor. An example would be any of the 8 or 9 foot Sound Labs speakers. Omnidirectional speakers will never give you the ultimate image in any room and you have to use a lot of acoustic materials to get even close. 

Next is an issue you will not see covered often and that is identical sonic performance between the two channels. No two speakers are exactly alike and you can not place them in exactly the same location. They will have different amplitude response patterns or rather, they will not have identical frequency response curves. When one speaker is louder than the other at any given frequency the image is smeared towards the louder speaker. Thus the image can be smeared back and forth at various frequencies killing the 3rd dimension, that last 10%. The third dimension is not instruments at different distances away from you, any system can do that and much of it is artificially created by the mixing engineer with echo. The 3rd dimension is the sense that and instrument or voice is a 3 dimensional object in space. If that space is full of reflections, echo and amplitude smear you will not be able to delineate the 3rd dimension at all. This is the state of most systems including some incredibly expensive ones. The only way to achieve sonic symmetry is by measuring each channel independently then adjusting amplitude over the  frequency range. I limit adjustments to between 100 Hz and 12 kHz. You do not have to have a flat response, you have to have identical frequency response curves. Flat actually does not sound so hot. Studies have shown that the best response curve in most residential situations is boosted bass below 100 Hz with about 2 dB/oct attenuation above 1000 Hz. 

Imaging is always going to be best at the listening position and on a line perpendicular to the speaker axis through the listening position. There is no such thing as a "wide sweet spot". However, it would be nice to be able to hear the far speaker clearly and again line source speakers are best at this because volume does not fall off near as drastically as point source speakers when you move away from the loudspeaker.  

As Mike Lavigne suggests accurate bass is a vitally important aspect of system performance and easily the most difficult portion of the spectrum to optimize. The reason is interference patterns in residentially sized rooms and resonance of this that and the other. Bass is incredibly physical. If I play a 30 Hz test tone at 85 dBs you can hear a symphony of buzzing and rattling in the house. This is usually completely masked by the music. I attack only the rattles I can hear. Room control can only do so much and subwoofers often do more damage than good, but sometimes you have to dance with the devil especially if you were to chose another ESL, and that is a whole other subject. The problem with your MLs is they cross to a dynamic driver at 375 Hz, right in the most important part of the midrange. Remember 256 Hz is middle C! The electrostatic portion of the Ethos can not handle lower frequencies because it is curved. An enclosed dynamic speaker is dramatically different than an ESL. The difference below 100 Hz can be gracefully dealt with, but above 100 Hz not so much. IMHE no ESL can gracefully handle bass below 100 Hz and this is where you have to dance with the devil. 

@toddalin  This is a great point. You can not know what SOTA imaging is until you have heard it. You have to know what you are missing and you have to delineate the problem in order to attack it. I have many studio recordings that you can tell the vocalists and instruments are in totally different environments and probably recorded at different times and frequently in different studios. I focus on live recordings or recordings in which the entire band is playing together in the same room. Great imaging helps to delineate individual instruments. A good live recording with a horn section is a great example. A top notch system will allow you to identify each instrument in space. Most systems show you the horn section, but you can not separate the instruments easily, the same applies to vocal sections. The spatial cues are usually there, but acoustic errors can easily overcome them because they are at a much lower volume. IMHO there is no such thing as too much acoustic treatment. An anechoic chamber is better than a poorly treated room.  

ATCs are known for their off axis sound. Sealed box.

@mahgister Please answer this simple question. A recording of a trio. Guitar, Bass and Sax. The recording engineer has mixed the final tape to have all three mics/instruments playing an equal signal from left and right channel. This puts the sound of the recording with all three instruments in the center of the stage. Are you claiming there is any stereo equipment or room treatment, or combination of each that will produce a playback in my listening room where the three instruments are spread out across the room, and for good measure, the sax is in the center and five feet in front of the guitar and bass? That is what I called into question with the statement, if it’s not on the recording, it’s not in your listening room. Cheers

The notion that everything remains at the mercy of the mastering tech and his recording’s limitations/inadequacies is a bit time warped and assumes that everything remains the same as it was 50 years ago

Some very smart guys at Dolby, DTS, Yamaha, Sony, etc got together and advanced technologies in object based/spatial audio to address just this. You would need a minimum of 6 speakers ( 2 fronts, 2 surrounds, 2 heights) to do justice to their spatial upmixing codecs. The speaker count would go up from there depending on how nitpicky one gets. If you have a native spatial mix, that’s great. But, they will try to salvage even crappy stereo mixes.

In other words, these codecs can decompose the recording and "spread it out" in a 3-D dome (aligned with your multi speaker perimeter) and create all kinds of depth wise layering, spatial nuance/cues and detail, that’s simply impossible in stereo.

If you are an ardent believer in 2 speakers only, BACCH can do a relatively dumbed down version of the above mentioned and offer something relatively convincing.

Some new FPGA dacs (hrtfs, whatever proprietary code’s in there) used in purist stereo will try to create an even more dumbed down version of the above mentioned

You could try to help things out with speaker design (concentrics are an example), positioning, etc. For example, if you have speakers flat against a wall and sit flat up against a wall (no 6 to 8 ft of space behind you), everything goes to sht from there, etc.

+1 to mijostyn post ...

The third dimension is not instruments at different distances away from you, any system can do that and much of it is artificially created by the mixing engineer with echo. The 3rd dimension is the sense that and instrument or voice is a 3 dimensional object in space. If that space is full of reflections, echo and amplitude smear you will not be able to delineate the 3rd dimension at all. This is the state of most systems including some incredibly expensive ones.

I understand his point here but we must had the right balance between all surface (reflecting-diffusive and absorbing) then we can have too much room treatment if one of the three factor is unbalanced with the others for a specific room geometry size and content ..

A good live recording with a horn section is a great example. A top notch system will allow you to identify each instrument in space. Most systems show you the horn section, but you can not separate the instruments easily, the same applies to vocal sections. The spatial cues are usually there, but acoustic errors can easily overcome them because they are at a much lower volume. IMHO there is no such thing as too much acoustic treatment. An anechoic chamber is better than a poorly treated room.

I used my own mechanical equalizer with 100 distributed resonators located at specific places and this is more than passive acoustic treatment. We can create not only good imaging and holography ( the third dimension which is the sonic volume of each instrument ) but the end goal more than imaging done right is the listener envelopment (LV) Source width auditory (ASW) ratio.

But no, an anechoic room is a dead space , unnatural, it is better a bad room we will improve ... ☺😊