ATC is for sure a different transducer practicing Black Flag orders; take no prisoners.
Chameleon in nature, as any change in component, cabling or source shifts the paradigm. That means room acoustics too. Move a chair and bang, different.
I’m speaking about the actives now: They are brutally dynamic, lightning fast (attack) and relentlessly revealing of timbre. The whole PRaT they deliver in spades. Not the most holographic transducer, however the soundstage is quite stable. With all systems operating optimally the larger actives will rearrange you.
Perhaps not for everyone. I’ve owned/own ATC 19A, 40A, 50As. Also have ATC 20 passives and they love tons of stable current.
Enjoy your hunt.