Edit: Heard it has to be 0.39v,

Most of my steppers were 0.4 - 0.38.
Only one, the one that missed most steps aka the Y axis, It was 0.378, Changed it now back to 0.389,
Seems to be better to be honest, the sound is a little diffrent i think, it may be just me.

With that ive also found how to measure it,
If the chip is facing down, the left second last pin and the POT screw.