1 month of waiting later and I have the HD now. I sold my regular Concero couple weeks back which I deeply regret but on first listen it sounds great. So great in fact I almost want to say it surpasses my vintage balanced parasound dac 2000 on first listen through hd600 on GS-X (I used to switch back and fourth between the regular concero and the parasound as they more or less traded blows). I can't believe it so far but will give it more time.
The seller of my HD unit doesn't have an answer as to why the serial number was removed from the bottom of the unit. It was clearly there at some point and removed
Black market out of the back of a van now for Resonessence gear? You know, 'cause they were getting shipped to bestbuy and fell off the back of the truck!