I have to agree with JakeWash. I have a 9 month and 2 year old and as soon as they get near my m80s, I tell them "NO" in an authoritative voice. My 9 month old likes to push on the grill cover, so I tell him "NO" and give him a gentle tap on the hand touching the grill.

My oldest has learned not to touch them and my youngest is slowly learning.

Receiver: Yamaha RX-V2200
Main: Axiom m80
CC: Axiom VP150
Surround: Axiom QS8
Sub: SVS PC13-Ultra