The tonality of the Immanis is - to my ears - neutral / cool. The midrange and treble are crisp, sparkling, with a substantial amount of treble energy. The bass foundation is substantial as well, although very tight, which provides a balancing act to what otherwise would have been an overly lean / bright palette to my tastes. To put things on a (subjective) perspective, on a scale 0 (pitch black) to 10 (white heat bright), I would put Immanis on 6.5, whereas SR1a and HD800 would be 7, Warwick Aperio 6.5, CA-1a 6, AB-1266 with Superconductor 6, Utopia OG 6, Susvara 5.5, X9000 5, HE-1 4.5, Valkyria 4.
The tone leans towards a studio tuning with little concessions to romance, I would not use "smooth" as a descriptor for the high frequency response, unless you compare to overtly bright cans. In my book, smooth comes with a pleasing roll-off and an organic texture, which I would not associate to the Immanis treble sound. I would describe Immanis treble as a pure, grain-less, liquid, agile.
The presentation is very big, open and propulsive, exciting. The sound breathes, and comes from out of your head like no other phones, except the SR1a with open-angled earpieces (terrible for bass, though). The transparency and detail is astounding, both micro and macrodynamics are startling. Imaging is the best I have experienced.
There is a good amount of body to the sound, more than the SR1a, less than Susvara, Valkyria, LCD4 or X9000.
Slam is good, yet not at the level of what the best planars can do in the sub bass, neither at the level of what the best dynamics can do on bass.
It is a true ribbon sound, stingy, insanely fast and resolving. They extract information from the recordings down to plankton level, but - luckily- they dont overwhelm / distract you like SR1a / Aperio. They are ruthelessly revealing, rather unforgiving. They are inducing an attentive, alert listening attitude rather than a laid back abandon.
The Immanis are very sensitive, responsive to changes in the setup (cables, electronics, power, software), so there is room to optimize a system around them tailored for one's tastes, where all I have noted above can be changed to some extent.
I sense they will love big-tubed electronics.
Furthermore, a remarkable aspect of the Immanis - which seems to be a characteristic of RAAL headphones - is that they respond very well to EQ (of which in general I am not a fan), to the point that they can be modelled into a very different tonal balance (like in an Abyss-level bass monster or a 'buttery smooth' X9000 midrange) without totally disrupting their unique nature or compromising their transparency. I bet when Mitch will have the chance of preparing some professional filters, they will be very much worth trying.