I would follow fungus' sensible questions / suggestions. You will need to know what "drivers" and how many such "drivers" you are dealing with. I would suspect that they don't take much current to drive but it is never wise to assume.
To be save, put a small resistor (1k for example) between the mega's output pin and all the drivers' input pins to see if that will work, if you cannot find the spec for the drivers.