Drv8825 max vref?

I have a set of Nema 23 motors and I was going to use the microcontroller I bought from your shop to run the setup but I’m a bit stumped. The motors have a max A/Phase of 4.

So going by what I saw in the video on this site for setting up the current limit https://www.v1engineering.com/assembly/ramps-wiring/ ,I am limited to setting the vref to .75 volts? Which would max out the Drv8825?

Am I doing this correctly?

If you have good fans on them you can run the drv8825’s at 1V sometimes up to 1.2V

Is the increase in voltage just to help the motors resist slipping?

more power overall