They claim that the noice to signal ratio is about 140dB, and that the closest competitors are at 95dB, so I guess that even the most sensitive IEMs/CIEMs will be without any hiss, and have the blackest black you ever heard.
The volume control is stated as a "state of the art" volume control so I would guess that there are not any channel imbalance even at low volumes.
What I do know very little about (nothing actually) is output impedances and how that influences sound in headphones / IEMs / CIEMs.
I guess that Jude will help us out soon, as he has stated that he will say more about this DAC/AMP (and I hope soon!).