I just commented on this in the official expanse thread but here’s my canned answer:
Utopia is treble peaked, muddied mids from unrefined bass as compared to Expanse. The details on utopia will feel brittle and thin compared to the weight added by Ex.
As to slam, if you hear these new cans (after 75-100 hour burn in) and think there is not good macro dynamics/no slam then I would argue that there is one of our up to all three things happening at once:
1- Your chain is potentially the limiting factor. A very discerning DAC and powerful yet slightly warmer than neutral amp is required to juice this fruit just right.
2-Your ears have been inundated with overbalanced and elevated bass via V shaped cans or EQ for so long that this is what you have come to expect/require as a baseline and see anything shy as inferior. When you hear the removal of distortion and muddying of mids due to low quality and over quantity of bass in the Expanse, the music becomes revealed in a way akin to removing a wet blanket from a speaker.
3-You simply prefer a heavier bass signiture than what is presented in Expanse/Stealth as a “natural normal correct live listening reproduction” of the music.
2&3 are hard to separate but they can be with attention and time. 3 is not “wrong” but a personal preference that you can EQ in to expanse if you would like, but I argue that heavily overbassed and V shaped cans have a much harder/impossible time EQ’ing that out to reach “natural” sound.