Hi. I have the 789 and I use the single ended input together with the SE pass through connected to my NAD D3020 amplifier. I use the Chord Mojo line out to 789 SE and sometimes I use the NAD C565BEE audio out to the 789 SE. In both instances, if the NAD is off, I hear a distorted sound through the 789 headphone out (both balanced and SE). If I turn on the NAD, the sound is normal. The sound is normal also when I disconnect the cable from the 789 pass through. Is there something wrong with the 789? Is there a short inside? Funny thing is, if I use the Mojo (with a digital player) then Mojo is connected to the 789 also with the pass through cables connected to the NAD, even if I turn off the Mojo while the digital player is playing music, the music goes through to the 789 to the headphones but with a distorted sound.