What I meant was, can the Pioneer downscale the video to 1080p. But also does this happen with non-4k discs?
Only the Main HDMI output from the Pioneer should be connected to the TV. The audio only output would be connected to the 975. Which would split the audio and video. The HDMI output from the 975 goes to another input on the TV, which is usually the HDMI ARC, to complete the HDMI handshake.
_________________________
Main HT <> 976 <> 7200 <> Ultra-X12 <> sapphire ST2 mkII RF/LF <> sapphire SC center
sapphire ST2 mkII SBR/SBL <> sapphire SS SR/SL <> Verizon/DVR <> Vizio M70Q7 <> Oppo UDP-203 <> Amazon 4k Fire TV