Well, I am not too big to admit I may have jumped the gun earlier with my impressions of the DX100.
I have been listening to it pretty much continually and even though my Cowon is very good, the DX100 is Soooo much better.
I was initially expecting to be floored by the DX100 as soon as I powered it up and was extremely disappointed when I wasnt. Since then I have slowly learnt that the DX100's magic is in its subtleness - songs that you thought you knew, suddenly sound new as you discover intricacies you weren't aware of before.
Somehow (and I cant quite find the words yet) the DX100 is just leaps ahead of any other DAP I have heard before. The soundstage is so much bigger (but not unnaturally so) and has a 3D'ness I've never heard in my music before. The instruments sound much more Real, fuller and weightier. I cant believe how good drum kits sound - every part of the drum kit sounds very different and obviously distinct from the other parts of the kit. Cymbals are incredibly brassy
I know this is a well used cliche but I have found it to be very true of the DX100...I have heard things in tracks that I know well that I have never heard or noticed before, as they have not been as obvious.
Hoe Down by Steve Martin - has a Tambourine in it that is set quite a way back in the centre - I've never really noticed it before and certainly never associated it as a tambourine.
Leviathan Bound by Shearwater - I had no idea that the keyboard instrument being played was a Harpsichord - it is so obvious now!
Also unlike the J3 I have not had the urge to turn on, let alone, play with the EQ settings
With the DX100, I never want to turn my music off...there is always something new to hear
My setup is
FLAC (16\24bit) -> DX100 (v1.1.7) EQ Off -> JH16Pro