Ety (positive) Rant alert
After my fair share of experimenting with various IEMs and open backs and for the last year spending my time with Moondrop Blessing 2, I can say that as far as I'm concerned, the whole "holographic effect" thing and that Ety are "2D/in your head" is utter trash.
To me it seems to be no more than a matter of insertion depth. I've adapted some tips to my Blessing 2 set for example to insert them deeper and guess what? The closer you get to the eardrum, the less space between your eardrum and the tip of the earphone and the less atmospheric space you perceive.
To be clear I'm being facetious there, I'm not equating the two meanings of 'space' but it is an interesting correlation.
Conversely, using my ER2XR set with Shure yellow flames or comply P series tips and not even squeezing the foam, just bunging into my ears a couple millimetres (almost as if they're earbuds) provides as good isolation as my Blessing 2...AND the same holographic soundstage (except better female vocals, sorry Moondrop but ER2 blows away the mids game) and the bass is oowww so yummy.
Honesty just have a listen to something like Split The Atom by Noisia with your ER-whatever set half-way in and fully in. You'll see what I mean. I think there's a certain amount of reflection that takes place in the ear adding to that spacious soundstage width people bang on about and decide to blame earphones rather than fit.
And I bet someone out there would argue you can't separate the two - the fit of the earphone defines the earphone in practical terms. Well no because I just said you can use the ER series as an earbud pretty much (only recommended with foam tips, from my experience anyhow) and the frequency response is phenomenal whilst giving that soundstage presence you were about to dismiss.
Okie crappy rant over. Can anybody confirm either way and add some science to this? Am I insane? I mean I know I am but with regards to this I mean
Thanks, Dave