Immersiveness is a precise acoustic property not only in headphone but in speakers soundfield...
It is related to the ratio ASW/LV control in a room ...
And the fact that you attributed it to the speakers design is not false, because each type of speakers MAY contribute in his own way to an immersive experience , but this quality is first and last an ACOUSTIC concept and the result of an acoustic set of controls of the relation speakers/room/listener location , immersiveness is then not a speakers design concept even it is for sure related to speakers design concept ... Then as such we can use any speakers and make his experience "immersive" ... it could be easier in some specific room with specific appropriated design but ANY speakers can be associated with a relatively good immersive experience if we understand how to use the many acoustic factors related to this concept in a room acoustically controlled for them ... i learned it with big as with small two way speakers by the way ......But i could do it with ANY speakers type , it is only necessary to put them in the right room and right acoustic conditions ...
It ask for way more than few acoustic panels though in my experience ...
@mahgister --
Much of this, it appears, comes down to semantics and which meaning to ascribe to terms. It seems to you "immersion" is linked to acoustics predominantly, while to me it isn’t (predominantly). When you spoke, or rather wrote about "an immersive inclusive soundstage engulfing the listener with swmall speakers," I found it "stole" into the realm of mainly horn-loaded and to some degree panel speakers of considerable physical size, speakers that to my ears have been the only real way to experience a large radiation bubble of said "wash" of immersive, and indeed visceral quality.