The patch completely replaced the HDMI handshake code. Before the patch, the AVR-591 used an older EDID (Extended Display Identification Data) management system. After the patch, the receiver could properly negotiate with PlayStation 4, Xbox One, and modern 1080p set-top boxes without losing sync every 20 minutes.
The Denon AVR-591, part of Denon's highly regarded mid-range lineup, has been a favorite for budget-conscious audiophiles for over a decade. However, in recent years, a specific firmware update caused significant disruption for owners attempting to keep their units current or re-flash their systems. denon avr591 firmware update patched
The primary issue stemmed from a server-side change by Denon. As the manufacturer transitioned support for older models, the update paths for the AVR-591 became corrupted or inaccessible. Users attempting to perform a standard network update encountered errors that could freeze the unit, cause network modules to drop connections, or—worst of all—brick the receiver, leaving it stuck in a boot loop. The patch completely replaced the HDMI handshake code
For a receiver known for its robust power supply and solid audio decoding, this software hiccup threatened to render perfectly good hardware useless. The one persistent complaint: the patched firmware slightly
After applying the patched firmware, owners on AVS Forum, Reddit’s r/hometheater, and Steve’s DIY Hifi report the following improvements:
The one persistent complaint: the patched firmware slightly increases fan noise on some units. Denon’s engineering team likely relaxed temperature thresholds to prevent shutdowns, so the fan now engages 10-15% more often. This is considered an acceptable trade-off for reliability.