Got my HA-1 setup. No headphones yet. Just using it with my Parasound A23 amp and Kef LS50 speakers on my desktop. Using AudioQuest Carbon USB cable and AudioQuest King Cobra XLRs.
Very impressed so far! Absolutely zero noise, just beautiful music. I previously had an M-DAC and this is another level. Crystal clear sound, cohesive, and to my ears very musical.
Thanks Oppo. What a bargain this thing is.