I have a similar setup but I use 2 mixers. Not sure if this is an option for you. The only way I can listen to both PC and Traktor is to do this. I run from PC to secondary mixer Line 2 and from primary mixer master out to secondary mixer Line 1. Then I run from secondary mixer main to monitors and secondary mixer record to PC. If you are hearing the timecode, then you are recording pre-traktor. Not sure how the A6 output is set up by with my A4 I set up Traktor with my outputs as: Mixing Mode-external, Output deck a - L out:ch a left, R: - ch a right, output deck b - L out: ch b left, R: ch b right. Seems you should have the option to set up the front output in the same manner. The A6 is setup to run from aux out to PC to allow for internal recording in Traktor. I may be wrong on that but I believe that to be the case.