Will a 12v 2 amp device work with 12v 2.5 amp power cable?
Providing that you maintain the same voltage and above all, make sure that the polarities are the same, yes, it should work. It's OK to have a little more power available than the device requires but it shouldn't be less, which can cause the cable to over heat or cause undue stress on the device itself. It sounds as though you're using a wall adapter to run something, and the extra .5 amp capacity should be OK. But, when using a wall adapter, always try to keep as close to the rating of the device as possible. Wall adapters that provide more power than what's needed, can over heat because the extra power isn't being used. It's just being converted to heat. Since you're within 20 percent of the device's ratings, this shouldn't be a problem.