Sad but true

https://youtu.be/fTeTodXG-As

Ah the MH1, predecessor to the legendary MH755.

No need. People who do actual science, interested in the furthering of knowledge for everyone via transparent academic research, rather than secretive industry insiders preoccupied with lining their pockets and an aversion to sharing data except to a select elitist few with NDAs, have already made their research publicly available. So that's a positive group delay audibility threshold of ~1.5 ms for actual music signals, which few headphones will exceed.

So you have zero evidence to present to back up your claims, got it. That's not how science works.

Do you have any evidence excess group delay at these levels is audible?

>many popular headphones (audeze, hifiman, sennheiser etc) have large portions of nonlinear and non- minimum phase response within their operating range.

Can you please post excess group delay measurements of all these 'many popular headphones' with 'large portions' of non-minimum phase response?

>I mean I would say a 5ms delay in the low frequencies in those plots is pretty significant...

That's measurement noise. See here.

That's because they're 2-3 dB above Harman over a broad range of frequencies right where our ears are most sensitive (upper midrange / lower treble).