KSTR
Major Contributor
So you are saying it would make a difference if you had a perfect amp by this definition (with some 1MHz++ bandwidth) and then put a, say, 50kHz 2nd order lowpass in front of it, on both channels? No way! Actually the group delay when using the LP only on one channel is inaudible.Our ears hear sound to a frequency limit of 20kHz, but we hear phase information to the equivalent of about 300kHz. This is why it is important that an amp have as flat of a phase response up to at least 300kHz. This range corresponds to the very small microsecond phase shifts that the folds of our outer ear (pinna) impart to sound waves right before they enter our ear canal. Note that the pinna is asymmetric and it is this asymmetry that enables us to psychoacoustically locate a sound source in 3D even with only one ear. There are many research publications by the military that show the ability of the human ear to discern microsecond phase shifts for the purposes of localization of sound sources (audio imaging and sound stage as we like to call it). So an amp and speakers may not be asked to reproduce frequencies above 20kHz, but they should do so while preserving phase coherency up to 300kHz. Maybe this is why DAC clock jitter matters?
You need several 10's of microseconds to even notice a microscopic center image shift to one side (with headphones, with speaker again: no way) and that effect is completely benign, no change of soundstage or imaging
You need to put up some serious evidence to your claim.