It makes sense comparing Sony STR-DH590 vs Onkyo TX-NR595 because they both are able to give some premium features.
A significant difference between the receivers in the number of channels, Sony STR-DH590 has 5.2 versus 7.2 for Onkyo TX-NR595. Regarding power, then STR-DH590 has such a W/Ohm ratio - 145/6 when TX-NR595 has a power of 80/8, 170/6. The THD is 0.09% for the STR-DH590 but 0.08% for the TX-NR595.
Characteristics of digital to analog converter (DAC) are different, 192 KHz/32-bit for STR-DH590 and AKM 384 KHz/32-bit for the TX-NR595. Only the TX-NR595 supports Bi-amping feature. Each of the AV receivers can transmit an audio signal directly to the amplifier and bypasses any DSP processing.
Only the Onkyo TX-NR595 can connect to the Internet via WI-FI. Rivals from our review have Bluetooth support. Only the TX-NR595 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. The TX-NR595 can scale the input HDMI signal, unlike the STR-DH590. The HDR standard - Dolby Vision is supported by these receivers.
The Sony STR-DH590 has 4/1 HDMI inputs/outputs versus 6/2 HDMI connectors of the Onkyo TX-NR595. 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-NR595 has a built-in phono stage for connecting a vinyl player. An ECO mode is not present in each of the AV receivers. The setup assistant will help you configure Onkyo TX-NR595.
Only the TX-NR595 has a Dolby Atmos multichannel audio format support. A surround technology DTS:X is supported only by the TX-NR595.