AVR-X8500HA & AV8805A HDMI 8K Upgrade All Image Credit: Denon and Marantz. Well it looks like we are on a roll for 8K upgrades, HDMI 2.1 support and the fix for the HDMI 2.1 bug. This hardware and firmware upgrade for the Denon […] AVR-X8500HA & AV8805A HDMI 8K UpgradeMay 28, 2021 in Equipment / News tagged AV8805 / AVR-8500H / Denon / HDMI Upgrade / Marantz by fromvinyltoplastic