This looks like Ikea, you can buy doors for this. Secure them with some straps you can find for this purpose on Amazon (or anywhere else). Don't worry about anything until 6mo old. Anything on top is out of reach until at least 12mo old. Congrats!
Vinyl and LPs - Analogue Music Goodness
A community discussing turntables, vinyl and the art of listening to high-fidelity music on spinning platters.
Dropping more of the weight into the bottom will alleviate the admittedly small possibility of tipping
Peep that Grizzlies blanket! But in all seriousness, I have 3 kids and I have no clue how to lock up my nice things. They always find a way.
I had what I find out now was a very rare stereo in the U.S. One of my funniest (now) stories is the time I was on a phone interview and my son who was about four at the time decided to come up with a screwdriver and proceed to climb this rack system like it was the Matterhorn. Since I was on an interview and a corded phone, I couldn't just stop him because he was about ten feet out of my reach. I have no idea what I actually told that lady in the final minute of the interview because my brain was trying to figure out how to stop a diapered spider man. Needless to say, I didn't get the job. But now I have a story. You nailed it, they always find a way.
Are those Kallax shelves from IKEA? If so, they sell door inserts that could likely be reinforced with baby-proof door latches.
It's also good practice to secure any furniture to the wall with anchors.
For the speakers, you could do something creative with wall mounts (Either to the wall or the shelves themselves)