Thanks for the tips, Tony. I'm pretty sure it's 8ohms for home theater. I once installed some weird 6ohm boat speakers in a shower, but the amp could handle it and it worked, so hey!

I was wondering if that was something to handle the distribution of the audio to each driver. Makes sense that it's a crossover.

I'll look into the car speakers. Unfortunately it looks like my receiver's rating is for 6-16Ω, so I'll have to account for that in my search. Thanks, folks!

I'm also hesitant to mount things straight to drywall, and given how close it seems I'd need to put an anchor to the cutout, I'm concerned that it would blow out the drywall. Perhaps some toggle bolts... I'd also need a good way to attach the grill. I could do construction adhesive, but I'd like something a tad more removable than that...