How does anyone determine this.
This is an hard topic.
In my tests and when I’m “on the hunt” I try to focus on the small things, like small sounds in the backgrounds (as how clear and detailed they are), how soon can I hear them, for how long I can hear their fading, etc.
Another good way, for me at least, is how stable and full is a voice on hard singing part.
On some headphones I can hear way more subtle pitch change, more “cracks” and in general it sounds “worse” on live recordings.
A prime example is Opeth’s Ghost of Perdition live at red rocks: it sounds almost perfect on YouTube via my bt headphone (PXC 550 II). The jazzy parts with clean singing are solid, just a little uncertainty but in general pretty good.
On my speaker setup it’s also pretty solid.
On the Arya SE from the Bly ray disc (connected via coax to the K9 pro) it almost makes me cringe… Mike voice crackle all the time, he is out of pitch and also the closure of every phrase is blunt and pitchy.
On the Sundara the results are similar, but not on the same level.
A good studio song to test this is Haken’s The Path. It’s a piano and voice song mostly, and the singing is quite “fragile”.
Not sure if that’s actually a good way to explain what resolution is, but at least it seems to fit.
IMHO not something you want at the level of the Arya SE on every headphone you own.