When you hear the Mk2 wih the V3,I wonder if you experience hissing while the music is playing?
I auditioned both of them together. Although the sound was amazing, I couldn't get around the little hiss playing in the background.
FYI, I don't hear a hiss though when not playing anything/the track is on pause.
I own both the AK100 and Mk2, and through the V6 there is no hissing at all. Background is the darkest and quietest out of other DAPs that I've tried/owned. Maybe it's your recording/file source?