These boards control stepper motors without any current sensing technique. They rely on your using the correct voltage on your power supply to generate the appropriate current in the motor coils.
If you use the correct voltage, you will find that these controllers do an excellent job of operating most low speed, low current stepper motors very quietly and smoothly.
AR-SS1010 series USB Dual 1000 mA Unipolar Stepper Motor Controller (not current regulating)
AR-SS1010 series USB Dual 500 mA Unipolar Stepper Motor Controller (not current regulating)