My bro just got his D10 today, only took 4 days. Gotta love em for the speedy shipping.
I did a quick comparison and obviously the D10 isn't burned in at all. My D4 has about 60 hours on it and as far as using it as a usb dac/amp it clearly sounds more open and dynamic with the mids more upfront. The D10 sounds recessed in comparison. But again, it's not burned in and I suspect it will open up nicely. This is not to say it sounds bad by any means. In fact, out of the box it sounds really nice, but as a dac with some hours on it, imo the D4 sounds quite a bit better than the D10 out of the box.
I wasn't able to test just the amp sections because, understandably, my bro wanted every piece of it and literally ripped it out of my hand. lol
For the brief test I was able to do though, I was impressed with the D10 and am looking forward to hearing it in a couple weeks.
Wish I could have given a better impression, but I just didn't have enough time with it.
Source: foobar2000 and RS1i