I listened to it for over 5 hours today, total bliss to my ears. Very neutral sounding, hiss free, it just let's the music sing. I played it flat with the exception of a few poorly produced tracks on Bandcamp. I used the BBEViVA2 setting for those to add a little more weight.
The D paired well with my MF200'S which was surprising considering someone said the D was bright. My MF200'S sounded bright when I first tried them but I could just be getting used to them as they're pretty new or it could be the Colorfly C3 I paired it with (most likely).
I threw every genre at the D (all FLAC / 24 Bit FLAC) I could think of and it coped admirably with all of them. I particularly loved the bass depth, nice and deep, well controlled with no boom. I put on the 'Kauan - Sorni Nai' album to hear the first track, I ended up playing the whole thing, it just sounded lush and it enveloped me, I couldn't turn it off.
Unit weight is not an issue for me, I had it in a shirt pocket for a couple of hours, it's nice and compact.
Scrolling is not A1 but perfectly usable once you get the knack. Personally, I don't think it needs an amp, it seems like overkill and would make it less portable in my eyes. I wouldn't want to change the sound and it drives my headphones with ease.
I'm going to pair it with my AKG550'S in the next couple of days and experiment a little with it. I think it will pair really well with the 550.
This is just my initial impression of the D and it's just my opinion of it. I'm by no means an expert. I would definitely audition it if you're in the market for a new DAP when it becomes more readily available.
I haven't tried it with iems as I'm prone to infections when using them so I cannot comment on their performance.
If they can sort out the scrolling via firmware and if cost effective cases etc become more available, I'll be pretty happy.
Probably not that much help, but that's my first impressions regarding the D
