Been looking into changing the Z axis and extruder stepper drivers from A4988 to TMC2100 (just ordered 2). So I searched stuff about it and came upon https://www.youtube.com/watch?v=H41hIXdB6js this video that shows this upgrade on MKS GEN_L board on Ender 3. He takes out all the jumpers out and then set Vref from max current of the stepper motors (for Ender 3 XYZ 0.84 and E 1A) and inverts the steppers from Marlin code. As the Z and E A4988 trimpots were setup to different values I should probably just not use max 1A current for both. From what current value I should calculate the Vref from?