Any tips to help our litter box smell like roses?

We just got two new kittens and one of them has the stinkiest poo. I assume their food is disagreeing with them. We bought crazy organic hippie cat food. It was about 40$ for a small bag. We will switch to different food once we run out.

Any tips on minimizing the stench from the litter box until then? It is in the basement with me and it is bad.

But I woke up to a kitten licking my feet this morning. I love cats!