I've used the D10 before, but not recently and can tell you the difference between the DAC used in both amps. Firstly, the USB dac cable is a love affair with me and I feel that it will be a great addition to a lot of computer set ups. There is nearly no noise in the signal and it fits anywhere. I use it with an iBasso T3D (love) which drives everything under the sun (in IEM land) perfectly.
Ear impressions: the first thing I noticed with the USB DAC cable is that it is incredibly smooth. Gobs of midrange detail, but smooth with the same earphones that only moments before (out of the iPod touch or amped S:Flo) were throwing up gritty treble detail. After a lot of listening, I can tell you that the top end is rolled off by several decibels. It isn't enough to ruin music and some people may like it. If you have the SM3 or EM3Pro or another earphone with 'smooth' highs, the USB cable isn't the best choice. For ETY, UE, FitEar fans, however, I think it is a great match. For the money, the USB stick is unbeatable and I use it almost all the time.
Personally, I'd prefer more top end detail, but that is Robert's decision. Just like the S:Flo, HiFiman, and some other sound designers, the Headphonia USB DAC cable is 'smooth' up top. Those who like it will love it - those who don't will probably move on.
