By definition crossfeed narrows soundstage instead of widening it

Fair enough, thank you for sharing

Well according to u/oratory1990, whose an acoustic engineer with a phd, it headphones are minimum phase

For IEMs, changing the insertion depth changes not only the resonance peak but also the treble frequencies by 3-5db. That's why the Z1R treble is so divisive. I believe crinacle or some other reviewers have the measurements for that.

For over ears, anecdotally my left and right ear HRTF is different enough I can hear the difference between them when doing frequency sweeps.

Since headphones are minimum phase devices, all those other things, including separation, speed, imaging, and soundstage, do depend on the frequency response.

However it's simply that's we don't know how to fully interpret these information from a FR graph yet, and the FR measured does not equal the FR you will actually hear (due to HRTF from pinna gain for overears and resonance peak from ear canal for IEMs, since every person's ear anatomy is unique)

Aside from the fact that most modern well engineered DACs are audibly transparent, there's also the fact that you're comparing 2 DACs by the same company. FYI, the m1 macbooks are almost as well messing as the apple dongle.

Digital sound processing (aka EQ)

Ah a fellow Hong Konger!! Congrats on your list :)

With that price you can buy all three and still still enough cash to go on a vacation

>DAC quality audio

Wait till OP learns even airpods have DACs

Still a better review than What Hifi

/u/oratory1990

If you apply a EQ filter of 10db gain, then you should set a pre amp of -10db to avoid clipping. But then you'll obviously need to boost the volume to achieve the same perceived loudness, which might cause increased distortion or you amp not having enough power for the whole dynamic range. Though I doubt one can accurately quantify "macrodynamics" claimed by you/OP

Semantics. And what a weird hill to die on