Agreeing with what the other guys said, powering up the machine before mach is running is asking for trouble. The port flips and flops all over the place on startup. A stepper motor pulsing a few steps or a spindle starting up at random is one thing, but imagine a linear motor capable of travelling 5 meters per second with 500 pounds of thrust backing it up randomly deciding to blow through your limit switches, hard stops, workshop wall, etc...
The charge pump can protect against this, as well as requiring an external "enable" signal to motor and spindle drivers, but the safest bet is to always have mach running first!