> I think this is not actually a movement distance problem in the crossfader, but in speed fading (cutting or "switching on") the sound by software when the crossfader sends the value for the change.
...
Here is your problem:
> The buffer size is set to 21.3 ms.
That is a bit high for scratching. Your buffer should be as small as your system can handle reliably without audible glitches.
> I think this is not actually a movement distance problem in the crossfader, but in speed fading (cutting or "switching on") the sound by software when the crossfader sends the value for the change.
...
Here is your problem:
> The buffer size is set to 21.3 ms.
That is a bit high for scratching. Your buffer should be as small as your system can handle reliably without audible glitches.