Do you have an example of a specific headphone with the excess group delay measurements that show a significant deviation from minimum-phase? Just cause you mention that a lot of popular headphones have large portions of non-linear regions. Like I see the M1060 as an example but it's fairly minor. The HD600 and LCD2 graphs (other than noise in the bass region) looks like it's very much minimum phase.

Personally I don't put much stock into measurement graphs other than to get a general feel for the tuning so don't take this is as me being antagonistic. I'm just curious because I haven't really seen an example where there's a clear and significant deviation from minimum-phase.

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

Can you elaborate further? What makes it non-linear or non-minimum phase?

It would be nice if you could provide some examples and elaborate on what you mean.