Can I use a DC power pack (12dcv 3a) with an inline connector rated at 24dcv 2a?
Since the voltage rating of the switch is higher than the supply, it is NOT a problem.  However, since the supply CAN provide 3A, if the load draws this amount, the switch will get hot and may malfunction.  But even if the switch "malfunctions," the load most likely will not be damaged.