1.. this thing is quiet. Very low noise floor via USB. I am using it downstream of a USB galvanic isolator, which lowers the absolute noise floor on a lot of DAC's. Still the noise floor is as low or maybe lower than my W4S DAC-1 LE.
2. Sound is smooth and warm. Definitely on the other side of the spectrum compared to the W4S. Well, that's exaggerating, but the W4S is more neutral with hints of warmth. The Aune is characteristically warm I would say. The other DAC I have here is the iFi iDSD Micro. I would put it right in the middle of the other two totally.
3. Midrange is nice!
4. DSD sounds very very good, even if they don't have the true Native DSD mode engaged. Since there seems to be no way to disable volume control, I am assuming they are using the DSP pathway rather than volume bypass. Whatever the case, the result is excellent and I'm not really worried about it.
I haven't checked out the headphone amp yet. That's next on my list. Gonna plug in via balanced my LCD-X.