the Knob working, but on screen ( software ) the button dont move. i cant control the volume in record mode
Tha main Volume button in software ( Traktor 2 pro ) only can be moved by mouse, in S4 nothing happens
Not really. Just set it to a reasonable level (ideally less than 0dB) then you never have to touch it again, control everything with the S4 harware volume.
Exactly. There are two volumes to control. The software and the soundcard - those are independant of each other. If you have line thru and using the sound card the software volume will have no impact on it. Leave it set to avoid clipping and manage your volume thru your sound card.