Ah ha! The Little HiFi Terrorist syndrome.
a) Never leave the little one with the hifi alone at any time.
b) No flashing /blinking lights anywhere on the setup. It only attracts them
c) Keep speaker grills on at all times.
d) When the ability to crawl and walk comes to them, resort to a)
e) Give the 'I'm the Daddy' look when they are anywhere near the setup
f) If e) does not work then give the 'I'm the Daddy' sound (this can resorts in tears as they think they are in trouble but is usually effective and they soon learn the hifi is out of bounds.
g) Always be 1 step ahead.
f) In the mornings, get up before they do and secure your terrority until they learn the hifi is out of bounds
i) Some has used fireplace grills to protect their kit, I never needed to. The Daddy look and sound has always worked for me but depending on how stubborn one's child can be it could be worth considering.
It is a ongoing process, the older they get, the braver the become, as my 4 going on 40 yr old child sometimes plays she don't hear, but i shall not be broken and nor will my kit
Or you sell your kit and look to rebuild once the little one is of the age of understanding.