Right the internal DAC output voltage is low. I have a Audio GD NFB7 which has 5V output voltage over XLR. The Moon is about 10db louder with the GD DAC. But again with High Gain + Internal DAC I will never reach 80db volume with my Abyss. And I think with HE6 it is also no problem.
Well noted your input Trance_Gott