How many HomePods Mini can I connect to Apple TV?

Greetings, JMarszal.

Welcome to the Apple Support Communities. We can understand why you’d want to know if you are able to set up more than 2 HomePods. 

“Pair two HomePod mini speakers or two HomePod speakers in the same room to create left and right channels for an immersive soundstage.” Set up a HomePod stereo pair 

We hope this helps! Thanks for being a part of the community.

Sincerely.

I have four HomePods. I have my first pair selected as my primary output in the audio output menu. My issue was that one pair in front of the tv wasn’t loud enough. I wanted a pair near where I set. I added a second pair near the sofas. I set the pair near the sofa as the primary pair and calibrated from where I sit. In the audio menu, I choose the second pair in front of the tv. You can adjust the volume level on each pair separately. One issue is that the second pair gets dropped from time to time.