Denon and Marantz introduce 8K HDMI 2.1 upgrade for AV receivers : r/hometheater
MARANTZ NEW NR1200 2 x 75 Watts A/V Stereo Receiver w/HDMI | Accessories4less
Denon SPK618 HDMI 2.1 Adapter for Denon Marantz AVRs, 8K/60hz & 4K/120hz + Cable | eBay
Report: latest AVRs from Sony, Denon / Marantz, Yamaha, etc. have a bug in the HDMI 2.1 chip - unable to pass through the 4k120hz HDR10 signal (german article) : r/xboxone