Just to clarify something on the current requirements, a 5A stepper motor won't draw 5A from the power supply, except in very specific circumstances which are not actually likely to occur.

Say a stepper is rated 5A at 10V while stationary (nice round figures for simplicity, but voltage is likely to be 3-5V for most common steppers), that means at idle, it will consumer 50W (5V x 10A).
If you power that via a 50V transformer, that means at idle the drive is only going to pull 1A (50W/50V). (assuming 100% efficiency - typical efficiencies are going to be in the 90s)

However, once the motor starts spinning, the motor requires more voltage to maintain the rated current due to the generated back emf, so at some point the drive will reach a point where there is not enough voltage for it to maintain the full 5A current, and this is the point where maximum power supply draw will be pulled. As you move above that point, which I'll call the peak power point, current draw will actually decrease.
However (yes another however!), stepper motors are not that efficient, so in practise the current actually drops of before reaching the peak power point, due to that pesky inductance which limits how fast the current can be changed in the coils.