I was wondering about the importance of linear phase in this situation. On one hand, I learned that linear phase is important to minimize distortions due to the different group delay. On the other hand, the phase difference is very small for frequencies up to 20 kHz (relevant for audio) leading to small delays which will probably not be noticeable. Is this reasoning correct?
Close-up of the phase vs frequency from 20 Hz to 10 kHz on a linear scale:
Will a Bessel filter with a highly linear phase like the one shown at the beginning of this document make more sense as an input stage?