An affordable AV receiver is always a good option to consider, so Onkyo TX-RZ840 vs Denon AVR-X3800H comparison definitely makes sense.
A significant difference between the receivers in the number of channels, Onkyo TX-RZ840 has 9.2 versus 9.4 for Denon AVR-X3800H. Regarding power, then TX-RZ840 has such a W/Ohm ratio - 180/6 when AVR-X3800H has a power of 105/8, 135/6. The THD is the same and is 0.08%.
Characteristics of digital to analog converter (DAC) are different, AKM 384 KHz/32-bit for TX-RZ840 and 192 KHz/32-bit for the AVR-X3800H. Both the TX-RZ840 and the AVR-X3800H 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 Apple Music service is implemented on considered devices: AirPlay, AirPlay 2. Spotify can be used on each receiver. The TX-RZ840 can work with the audio stream from Deezer, TIDAL, Pandora, TuneIn Radio, and the AVR-X3800H can receive a content from Deezer, TIDAL, Pandora, SiriusXM, Napster, SoundCloud, Amazon Music, Amazon Music HD, MOOD:Mix.
HDMI signal transmission in standby mode is implemented in each of the devices. The AVR-X3800H can scale the input HDMI signal, unlike the TX-RZ840. The HDR standard - Dolby Vision is supported by these receivers.
The Onkyo TX-RZ840 has 7/2 HDMI inputs/outputs versus 6/3 HDMI connectors of the Denon AVR-X3800H. 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. The TX-RZ840 supports the protection of digital content of the standard HDCP 2.2, versus HDCP 2.3 in the AVR-X3800H. These compared receivers have a built-in phono stage for connecting a vinyl player.
The TX-RZ840 supports 3 Multi-room zones, versus 2 for the AVR-X3800H. The TX-RZ840 supports voice control via Google Assistant, and the AVR-X3800H - Amazon Alexa, Google Assistant, Siri, Josh.AI. An ECO mode is only available for the AVR-X3800H. Both TX-RZ840 and AVR-X3800H 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.