Your Mini needs to go to one of the HDMI IN ports on your Pioneer receiver (as it's a source), not the TV.
I guess that would work since that's the setup I used to have. I'm just worried I'd be compromising image quality if it goes through my receiver first, rather than directly into the TV (as mentioned below regarding my PS4)
Your TV is via HDMI out (obviously)
from the receiver. Why do you need the optical connection? (is it supposed to provide better dynamics than the HDMI audio?)
I initially had my Mini connected with HDMI to the receiver, and the receiver connected to the TV. But when I got my new TV, I found out that in order to get HDR on my PS4, I couldn't have the image go through the receiver - so I had to connect my PS4 directly to the TV. I figured I might generally get better quality on all my devices that way, so I connected all my stuff directly to the TV, and I'm then using the optical connection to get sound from the TV to my receiver. On my PS4, this works perfectly and I get surround sound (note: at first it didn't work on PS4 because a sound setting was set to "optical cable". I changed that to "HDMI" instead, and voila, my surround worked. However, the PS4 is connected with optical, not HDMI
I've only used that for devices into the receiver that didn't support HDMI audio.
So, you're not using any of the speakers in the TV then, right? They're all connected to the receiver?
That's right, I only use sound from my speakers. Never from the TV, although I can easily enable that in my TV settings.
Did you do the audio setup in the receiver? If your receiver came with a microphone that plugs into the front, you place that in the middle of your viewing area, it'll do a sound check with all of your speakers and adjust the levels for the room.
Yeah, I have that microphone and actually just used it a few days ago to make sure that my center and rear speakers weren't broken. This was before I got my PS4 to work, of course.