It makes sense comparing Onkyo TX-RZ820 vs Sony STR-DH590 because they both are able to give some premium features.
A significant difference between the receivers in the number of channels, Onkyo TX-RZ820 has 7.2 versus 5.2 for Sony STR-DH590. Regarding power, then TX-RZ820 has such a W/Ohm ratio - 160/8 when STR-DH590 has a power of 145/6. The THD is 0.08% for the TX-RZ820 but 0.09% for the STR-DH590.
Characteristics of digital to analog converter (DAC) are different, AK4458 384 KHz/32-bit for TX-RZ820 and 192 KHz/32-bit for the STR-DH590. Only the TX-RZ820 supports Bi-amping feature. 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. Only the TX-RZ820 supports Spotify.
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. Both competitors are not able to scale the HDMI signal. The HDR standard - Dolby Vision is supported by these receivers.
The Onkyo TX-RZ820 has 7/2 HDMI inputs/outputs versus 4/1 HDMI connectors of the Sony STR-DH590. The HDMI Audio Return Channel (ARC) feature supports both devices. Unfortunately, HDMI eARC is not available on monitored devices. 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 TX-RZ820 has a built-in phono stage for connecting a vinyl player. A voice control is not available. An ECO mode is only available for the TX-RZ820. The setup assistant will help you configure Onkyo TX-RZ820.
Only the TX-RZ820 has a Dolby Atmos multichannel audio format support. A surround technology DTS:X is supported only by the TX-RZ820.