Traktor Audio 6 - output volume issue on one side of channel A

Hi everyone, I'm putting on this video because I'd like to see opinion of the other NI A6 users. I'm running Traktor 2.6.1 + this DVS setup you can see there. The right side (channel B) has no issues, but the other channel as you can see on the volume meter has lower output volume on left side - in this video both decks are playing same song and I'm just moving the crossfader from one side to another so you can see the difference. Things I've already tried to see what could be wrong: 1. Replacing the needle of left TT (channel A) - didn't help. 2. Connecting left TT to the channel B input on A6 - worked - channel B seems to be alright. 3. Conencting right TT to the channel A input on A6 - the issue is still there. So I can only guess, it shouldn't be the TT cables, it shouldn't be the needles. So I'm guessing the problem resides in the TA6 soundcard, what do you guys think?? Thanks for any answers...