It makes sense comparing Onkyo TX-RZ840 vs Yamaha RX-V485 because they both are able to give some premium features.
A significant difference between the receivers in the number of channels, Onkyo TX-RZ840 has 9.2 versus 5.1 for Yamaha RX-V485. Regarding power, then TX-RZ840 has such a W/Ohm ratio - 180/6 when RX-V485 has a power of 80/8, 145/6. The THD is 0.08% for the TX-RZ840 but 0.09% for the RX-V485.
Characteristics of digital to analog converter (DAC) are different, AKM 384 KHz/32-bit for TX-RZ840 and Burr-Brown 384 KHz/32-bit for the RX-V485. Both the TX-RZ840 and the RX-V485 support Bi-amping. Each of the AV receivers can transmit an audio signal directly to the amplifier and bypasses any DSP processing.
Both models have the ability to connect to the Internet via WI-FI. 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 RX-V485 can receive a content from Deezer, TIDAL, Pandora, Napster, SiriusXM.
Both AV receivers support HDR10 technology (High dynamic range). 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. The RX-V485 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 4/1 HDMI connectors of the Yamaha RX-V485. 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 RX-V485. The TX-RZ840 has a built-in phono stage for connecting a vinyl player.
The TX-RZ840 supports 3 Multi-room zones, versus 2 for the RX-V485. The TX-RZ840 supports voice control via Google Assistant, and the RX-V485 - Amazon Alexa, Google Assistant, Siri. An ECO mode is only available for the RX-V485. Both TX-RZ840 and RX-V485 can be configured using the Setup assistant.
Only the TX-RZ840 has a Dolby Atmos multichannel audio format support. A surround technology DTS:X is supported only by the TX-RZ840.