I agree about the DF. I have one and really like it. It performs better with higher impedance phones rather than IEMs (e.g. 16ohm Miracles). It's not a match for my Audio-gd NFB-5.2, but for its size it's excellent!
Another full review here: http://passionforsound.wordpress.com/2013/03/03/audioquest-dragonfly/
Nice review. Not trying to nitpick, but after reading it twice, I'm still unclear that the author realizes that the computer volume must be maxed to enable DF's dac mode and pass the signal thru to an outboard amp. You then control the volume on the outboard amp, should you choose not to use the DF's internal amp. Also, it might have been nice to mention the DF has a 24 bit ESS Sabre chip and uses Gordon Rankin's (Wavelength Audio) streamlength technology. Lastly, unless I am misreading...I'm somewhat surprised the author was underwhelmed by SQ of DF to HD650s.
IMO, I agree the DF isn't as resolving as my PS Audio DL3, but that monster doesn't fit in my briefcase, either.
Oh well, as always...YMMV.