I know this will sound brutally sexist, but in my experience, it depends on the sex of the child...
I have two daughters, aged 3 and 1. Both have been exposed to both my systems throughout their entire lives.
The main floor system is a 2 channel HT, so all the gear is housed along with the TV, in a large cabinet. Bookshelf speakers (off the floor, but far from unreachable) have always been there. As an added attraction, the KIT41 speakers have a "woofer" with a copper phase plug, which is irresistible to little fingers... then again, it keeps them off the tweeters! This system sees extensive use, for such wonderous TV experiences as "The Wonder Pets", "Dora the Explorer", "Go Diego, Go", and a really good one (please forgive me, I am forever lost!) called "The Backyardagains" - this last one has great music, and has featured actual performers including guest voice overs by Alicia Keys etc. That same system (uses a Panny SAXR-25) runs the hockey games, and satellite based music channels etc. Both children have investigated the speakers to some extent, but because they were always there, they were not that attractive. Whenever a little hand touched a driver, I would simply say "please be careful", and usually was interpreted as "stay away" but was never enforced as such - touch, but gentle, as with the poor cat!
The real system (ie the one too ugly to be enjoyed by anyone with anything other than dim vision, and a STRONG love for sound...) lives in the basement. This is an unfinished space, and doubles as the "relief play area". I normally want to get the 2 monkeys away from my poor wife, who has to deal with them all day, and of course I want to hear my system too, so the 3 of us will go down there and play. Play involves a number of things. Music is always on, but they (OK, really only the 3 year old at this point) have some input to what music will be played during that time. My oldest daughter, Easton, has 3 current fav tunes - Bob Marley, Buffalo Soldier (this was the first piece of music that really connected with her, she loved it from the first time, and for several months would demand that song on repeat for the entire 1-2 hour sessions in the basement with me...), Pink Floyd, Another Brick in the Wall, and Shania Twain, Don't (which is really touching personally, because when my wife and I were on hold with the doctor's office, verifying her 2nd pregnancy, this was the song being played on the hold music - interesting irony!).
Only once has my oldest daughter abused one of the speakers in the main system. She walked up, and stuck her fist into the b200 Visaton, pushing it ALL the way back in its' travel, then walked away. My younger one, Cadence, went through a phase where she was interested in the wiring behind the baffles, but soon was distracted by Easton playing hide and seek behind them!
Here is Easton, roughly 6 months ago, auditioning for LoneWolf's job!
So, for my girls, early and frequent exposure to both systems, along with some guidance around "be gentle" whenever they go near them, seems to have helped.
Now the sexist part. My best friend has a boy and a girl, now roughly 6 and 4. He lost BOTH metal dome tweeters in the speakers I helped him build, and has had repeated amp dislodgement issues, with that 4 year old boy. Boys seem inherently more interested in deconstruction than girls.
Best of luck with it, some good advice added here by others!
