The Pioneer is a 4k player and the 975 is only 1080p for starters. Is the Pioneer capable of outputting 1080p? That's one thing you need to find out.
Also, it looks like there is an 'audio only' HDMI output on the Pioneer that can be used to connect to the 975 and the main HDMI connects to the TV for video. To do this, you'll also need to connect the 975 HDMI-ARC to the TV's HDMI-ARC input. This is so the TV can handshake with the Pioneer and the 975 together.
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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