^ Good notes, and I think what you describe lies within the range of what one might expect from the ff circuitry: specifically, "harshness...gone...smoothness".
Discussions of what makes equipment sound 'detailed' arise regularly, especially with respect to supposed digital artefacts heard by some with many delta-sigma DACs and with (so-called) artificially bright headphones and speakers. IIRC, FF achieves greater detail (Jan claimed), but your experience ("[gone is] sense of detail [and] energy") doesn't necessarily contradict this.
For example, one of my DACs produces more low-level bass information. This makes it sound as if it has "more bass" but in fact it is - like most DACs - ruler flat and neutral. I could say the same - to some degree - about my Audez'e phones, which produce more bass information and hence can give an impression they are "dark" or "warm". Of course, almost the opposite subjective result seems to have happened in your case.
What does disturb me a little is your note that it sounds "[less] up close and personal" :eek: I would have anticipated the opposite!
Anyway, the upgrade is one I have scheduled for this year. Thanks for the notes, which are valuable. To your astute observation it is "ultimately about list[en]ing preference" I would add it is also about individual variation in how we (our brains, probably) decode sound.
