Sorry Mythtrip, I'm not always that cranky. Merry Christmas.
Personally, I think that raising the heavy amps up high can be more potentially dangerous, than having them low, or on the floor. If they are up high, they can cause serious injury if they fall on a little one. If they are very low, or on the floor, they have no potential for falling on anyone, and any injury would only be to the amp, not the person.
Locked, ventilated cabinets recommended above may be good.
And no, I don't have kids of my own, but I do have to contend with my sister's kids, which were never well trained and she pays for it every damn day, and so does everyone else in the house. She did not train them at the proper time, and now she has what she has.
Also, even though my comments may have been harsh, the basis has validity. Children are quick learners. You can easily teach them to do what you want. They are highly intelligent compared to dogs and cats, and I have 4 cats and a 120 pound Rottweiler, and not one of them ever lays a paw on any of my audio gear. Even when I am not home, or through the night. And it is all within easy reach of any of them at all times. And no, I have never beaten any of them, and I love them. So I contend that since children are much more capable learners, it should be easy for them and you to handle this. I apologize for wording it bluntly. But I have watched what happens if this is not done, and it only gets worse.