If you have HDMI compatibility issues, use a modern HDMI 2.1 switch or an HDFury device to handle the handshake before the signal reaches the Denon.
Firmware updates for the legacy Denon AVR-591 often address signal processing and audio output issues, with support files available through the Denon Upgrades Archive, though the lack of network connectivity requires manual updating. While updates can fix bugs, experts advise performing a factory reset first to resolve issues like "no sound," as improper updates risk bricking the unit. For more information on available files, visit the Denon Upgrades Archive . AVR-591 - Denon denon avr591 firmware update patched
: Improvements to connectivity with older Blu-ray players and cable boxes. Denon AVR-591 Firmware Update Patched: What You Need
This often happens if the unit lost internet connectivity during an update or if a USB update was interrupted. For more information on available files, visit the
Denon no longer provides online updates for the AVR-591. If you run the "Update" function from the menu today, it will either fail or freeze. Do not use the network update feature.
If you own an AVR-591 and want to verify whether you’re running the stable patched version, follow these steps: