The most important factor in soundstage imaging

Wow Duke! You absolutely nailed it with regard to speakers!

I can’t add anything to do with speakers just a big thumbs up to your post!

What I can add is this, a little science...

Below 2000 Hz we locate sounds in the horizontal plane by time arrival at each ear. We can also figure out a lot of other info based on distortion off the pinea as well as comb filtering from the floor (locating sound front and back as well as high and low).

Above 2000 Hz, scientists have discovered that we use the relative loudness of sound. Our head is one huge blocking filter to HF sounds. At 30 degrees off axis the sound at 6000 Hz is 10 dB lower in one ear than the other - and this is what we use to calculate location. At higher frequencies the attenuation of the head can be as much at 20 or 30 dB - so we can very accurately figure out where a sound came from by using this method in addition to the other cues below 2000Hz.

Why do I mention this? Because minimum phase filters have become “du jour”. Even the lossy distorting next big thing called MQA uses minimum phase filters because marketing folks are trying to scare people with the INAUDIBLE pre-ringing boogie monster!

Minimum phase filters totally destroy the proper relationship between high frequencies and low frequencies. This is an imaging KILLER!!! High frequencies arrive much too late!!

Use only Linear Phase filters in your DAC if you wish to perfectly preserve imaging!!! (Preserve the maximum pinpoint imaging that was available from the source recording)

The real question is which S.S. amp has the correct soundstage? Some depth and dimension are artifacts that exist in part to the fact that your speakers are set out in your room and also from the room itself. Many recordings with depth actually shouldnt have depth or at least have less depth than is presented. At least this has been my experience.  

Forgot to add that a real enemy of speakers are crossovers which is why single driver speakers, when kept within its frequency comfort zones, are so good. All crossovers are problems, even the best first-order ones. It truly is like polishing a turd.

@jsautter

Passive crossover add quite a lot of phase distortion. However, so can resonance from whizzer cones and the like. So not a black and white thing except that phase distortion from a crosssover can definitely be an imaging issue.

The perfect solution is a phase accurate active speaker from ATC. Active crossovers can maintain phase perfectly - no discontinuities in phase and therefore a minimum of phase distortion.