It makes sense comparing Sony STR-ZA810ES vs Denon AVR-X4400H because they both are able to give some premium features.
A significant difference between the receivers in the number of channels, Sony STR-ZA810ES has 7.2 versus 11.2 for Denon AVR-X4400H. Regarding power, then STR-ZA810ES has such a W/Ohm ratio - 100/8 when AVR-X4400H has a power of 125/8, 165/6. The THD is 0.09% for the STR-ZA810ES but 0.05% for the AVR-X4400H.
Characteristics of digital to analog converter (DAC) are different, 384 KHz/32-bit for STR-ZA810ES and AK4458 384 KHz/32-bit for the AVR-X4400H. Both the STR-ZA810ES and the AVR-X4400H support Bi-amping. Each of the AV receivers can transmit an audio signal directly to the amplifier and bypasses any DSP processing. Rivals from our review have Bluetooth support. The Sony STR-ZA810ES has support for AirPlay, and its competitor in our comparison - AirPlay, AirPlay 2. Spotify can be used on each receiver. Compared AV receivers retain the quality of 4K/60Hz signal when transmitting from a source to a TV or projector. HDMI signal transmission in standby mode is implemented in each of the devices. Both rivals can scale the resolution of the incoming HDMI signal. The HDR standard - Dolby Vision is supported by these receivers.
The Sony STR-ZA810ES has 6/2 HDMI inputs/outputs versus 8/3 HDMI connectors of the Denon AVR-X4400H. The HDMI Audio Return Channel (ARC) feature supports both devices. HDMI eARC is available in each model. The Consumer Electronics Control (CEC) feature is present in most modern AV receivers and the models in our comparison are no exception. Both models support the standard HDCP 2.2. The AVR-X4400H has a built-in phono stage for connecting a vinyl player.
The STR-ZA810ES supports 2 Multi-room zones, versus 3 for the AVR-X4400H. The STR-ZA810ES supports voice control via Google Assistant, and the AVR-X4400H - Amazon Alexa, Google Assistant, Siri, Josh.AI. An ECO mode is only available for the AVR-X4400H. Both STR-ZA810ES and AVR-X4400H can be configured using the Setup assistant.
Both devices have support for Dolby Atmos multichannel audio format. The surround sound technology DTS:X is supported by devices under review.