|The offset of the volume knob is to|
ensure no peaking.
I have one little comment about the offset of the volume button. I believe that -10db on the master output is a bit hard. I normaly set it to around -3 to -5 db and I have never heard the limiter kick in... Traktor auto gains your tracks, so you should stay within the limits if you don't push to hard on the EQ.
Remember: It's always better to subtract sound on EQs then trying to amp it. ;)
Read the smashing article from DDT