Although, in my opinion, it shouldn't be hard to find something that sounds better than Klipsch, I'd keep what you have and train the toddler or maybe a gate can be fashioned when you aren't around to keep him out. What would keep the child from playing with the other brand of speaker? Putting something on a stand could even be more dangerous. In-wall is so permanent and lacks versatility but that would be the only fool proof option I can think of..... until the child got that tall Hopefully by then the interest in poking speakers would have gone away.

Here's why I say keep the Klipsch, they are highly sensitive, play loud without much power, your Yamaha is rated at 80 wpc and I'm sure that's a stretch, so if you go with another brand of speaker your perceived volume levels you can reach now will drop, I'd say significantly. Also, for just Rock the Klipsch can be fun. Another thing you might try is plugging the port which will tame the speaker until yu can move it away from the wall. Depending on the size of the port yu can use a rolled up pair of socks or maybe a towel for larger port.

It is also difficult to sell something used and end up with enough money to buy something comparable. Especially in this market and if the speakers have some years on them.

Take a look at www.emotiva.com their speakers are said to be an excellent value. They sell direct to consumer which gives the consumer a big bang for the buck. Then again, still contending with all I said above.

I'd also be afraid if you are a long time Klipsch user that other speakers may seem dull at first. Horns can sound pretty lively and if that's what you are used to a change could be difficult.

BTW... Welcome to the forum.