The increased bandwidth in higher resolution digital audio only increases the maximum frequency captured. It does not increase the bandwidth available to sound in the audible range. 44.1 kHz captures everything in the audible range, higher sampling rates capture exactly the same thing with the addition of frequencies we can't hear. Likewise there is nothing analog captures within the audible range that Redbook can't. We've been over this.
Can you please also explain why depth and height cues cannot be captured by Redbook but width cues can? What is the difference between them that makes this true?
Width - or span from extreme left to the exteme right and in between - can be most easily reproduced because they mainly rely on loudness of the signals, that is to say amplitude. Front to rear or depth perception has to involve some time cues - as the sound does not stop at some precisely "boundary" in any given real listening enviroment and echoes off walls etc mainly define the acoustics of that room. Rise time of redbook is approx 14 microseconds - or bandwitdh to 20 kHz. IF even I accept that this is "enough" - that means that this has to be maintained from input to output -from the sound waves impigning on the diaphragm of the microphone to the sound impigning on the eardrum - with every component in between fast enough to maintain that 14 uS risetime even under worst of conditions. In series as they are, that means each and every component does add so and so much delay/filtering - that means even the best equipment available does nor find maintaining that 14 uS easy - OVERALL.
There is no (pre)amplifier with infinitely short risetime or infinity bandwidth, no cable, and most certainly no microphone. Each and every component is slowing the original sound down somewhat - and this can CLEARLY be heard in redbook vs "higer speed" ( be it analog or digital ) : redbook is mostly flat surface as far as depth is concerned, under best of circumstances it has some depth that is definitely limited and does not match the same as analog or hirez digital and most certainly not live feed from the microphone.
This has no "boundaries" except for the real boundaries in that room ( walls etc ) - redbook never reaches not nearly close in regard of depth, because it can not convey those tiny time differences that do give us perception of depth - it is not amplitude mostly/alone. Sound after climax of an orchestra does "travel" - to the other side from the performers, to the rear wall, it reflects off the rear and side walls, etc - and these time cues are not nearly good enough with redbook. Or, they are - until
higher resolution version OF THE SAME RECORDING/MASTER is heard. "Perfect sound forever" brigade is VERY likely to say "it must be another mix/master" - because it is tiny tiny details at high frequencies that distinguish between "recording" or "real" - at least one octave above what redbook can provide. It is those barely audible entrances of strings etc that are on DSD audible and redbook only cathes up few micro(mili?)..seconds later - once the amplitude is high enough and/or the natural delay/ringing of digital filter has settled down - and clearly, their conclusion is - it MUST be different mastering ?!?!? I can not vouch for others as to how have they recorded and/or whether various resolutions of digital are really the same mix/master - when I listen to my original DSD128 master and its redbook counterpart derived from it (NO other stunts other than conversion of formats ) it does sound to me as described. YMMV.
The most significantly audible jump in quality in digital occurs from redbook to 88.2 or 96 kHz sampling frequency - this IS "night and day". Further increase in resolution is not that audible at first instant - but does matter in the long run. SACD or DSD64 is not decisively significantly better than redbook - but DSD128 IS.
Going up from here, DXD ( 352-376 /24 and up to 752/24 ) and DSD256 and DSD512 should finally close the gap between microphone feed and recording - because they introduce errors/delays that really should not matter anymore. There are bottlenecks long before the limits of these formats are reached, most dominant being the microphones. Slowly but securely more 100 kHz and beyond mics are appearing - even if one thinks it is a waste of everything and total nonsense, the use of such mikes means they cover audible band more easily than designs that struggle even within audible band.
ALL THE ABOVE MAKES SENSE ONLY IF AND WHEN SIMPLE RECORDING TECHNIQUES ARE USED - THAT MEANS TWO MICROPHONES. Any multimiking will introduce such gross time errors that advantage analog/hirez has over redbook may well NEVER be heard. Which limits the higher frequency rate digital to acoustic non amplified music - and certainly not pop etc, where natural sound without electricity practically does not exist. Here, the "tools" used are just too crude to warrant going to the above lengths regarding resolution of recording - but I would love to be proven wrong on this one.
All of the above also means it is not possible to make a remaster of say Kind of Blue that could challenge the modern recording on technical terms. It is what it is - great piece of music - but not anything to write home about regarding sound quality. It is about the best available at the time of its creation.
And precisely because it is great piece of music, I am going to listen to it now. Haven't in a long while - and will do it off vinyl which says mastered from original analog master tape. CBS roughly 90's. There were and will be digital "whatevers" - the real master for KInd of Blue is analog master tape and the best approximation is second generation of analog master tape - or so it used to be. New FAST digital may in the end displace it and analog record from the throne - but never redbook.