I agree the engineer won't take the risk to let any significant DC leave the dap to external amps or phones, simply for liability concern. But that design concept may compromise the transparency of the signal path. Fortunately, we do have the amp designer who is smart enough to design a DC servo circuit which can compensate for the "significant" DC without implementing DC blocking caps. When you have the caps eliminated from both the dap and the amp, suddenly the audio signal path seems just opening up with improved transparency. Once it opens up, everything else comes together (the details, clarity, smoothness, instrument spacing) as if the sound is no longer contained.
Well, this is already OT.
@Amos - Nice video review of the AK240. I actually like the looks and it does give that hi-tech impression. IMO, much better form design than the others out there.