Damn it's built like a tank. The thing weighs more than most headphones I have owned lol. But it feels solid too which IMO is a good thing
The sound is very clean. I didn't find it. Bright but it's definitely not warm like the x3.
I would say (and this is from memory) that it shares a lot of qualities with the ak100 in that it's a very neutral yet musical and smooth sound.
A little too much so for me with my current in ears, as such I am keen to hear the dx90 with its twin mono setup. I am hoping for a sound somewhere between the dx100 and ak100 sig. That would be the dream haha.
Anyway your mileage may vary but I was fairly happy with it overall and I even thought the ui was pretty dang good for so early in its development.