Why not just teach the kid to not mess with them? Yes, sounds impossible but I bet it can be done. When I have kids (soon, if fiancee has her way... ) I dont' plan on changing gear at all. Perhaps I am optimistic, but I think it can be done, with careful discipline, attentiveness, (and perhaps a fence of some sort... ? )... Sure, the seriously dangerous/expensive tube amps will be in a locked room, but the HT system will be in living room... do a search here on Agon, there's been some threads about this before... you can have your stereo and kid too... ;-)
-Ed
-Ed