The receiver is not new.
I don't get why 2 floor standing speakers would be used as a center channel?
The source is an HDMI usually from an Xbox, a Chromecast, or just a L/R CD input from my phone.
I thought I set them up correctly and I followed the installation of speakers automatic set up process I thought, but I could try again.
I'm using bare wire. I'm honestly not sure of the gauge. My guess would be 16 or 18. It's your standard looking clear insulation copper wire with 12 strands. I have a small spool of it, but the spool isn't labeled. The speakers are a spring clip terminal and the receiver has some sort of binding post terminal.
I appreciate the help. So are you saying all the speakers I have should work ok with the system?