I guess I’m doomed to not understanding this. I thought a phase shift like that shown in the plot where it dips is a negative shift which means a lag in the signal.
No a negative "-phase angle" is what’s with the speaker bass loading, totally different, the dotted line ("-phase angle") in this Tannoy speaker review https://www.stereophile.com/images/620Tan6fig1.jpg
This is "phase shift" on this Class-D https://ibb.co/jfd6tqy
(no - negative wording at all) Like a sub woofer being 180 degrees out of phase to the mains, easily heard when it back in phase
And no you wouldn’t hear it if the whole audio band were 70 degrees out of phase from bass 20hz to highest 20khz. But only the upper/mids and highs are 70 degrees out of phase to the mids lower mids and bass, and this is what many listeners object to when the hear Class-D, coincidence? I think not. And why many say Class-D’s make great bass amps, agree on that.
The only fix is to raise the switching frequency 3 x higher, then the output filter and the 70 degrees of phase shift go up accordingly 3 x higher to around 80-100khz then. It as simple as the that.
As atmasphere correctly said on another amp thread
"If you really want to get the soundstage right, the amp needs to have minimal phase shift in the audio regions so it will need bandwidth past 80KHz.