It makes sense comparing Sony STR-ZA3100ES vs Onkyo TX-RZ710 because they both are able to give some premium features.
Considered AV receivers have the same number of channels 7.2. Regarding power, then STR-ZA3100ES has such a W/Ohm ratio - 70/8, 90/6 when TX-RZ710 has a power of 175/6. The THD is 0.09% for the STR-ZA3100ES but 0.08% for the TX-RZ710. Both the STR-ZA3100ES and the TX-RZ710 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. Only the TX-RZ710 supports Spotify.
These units support HDR technology. 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-RZ710 can scale the input HDMI signal, unlike the STR-ZA3100ES. Dolby Vision technology found support only on the STR-ZA3100ES.
The Sony STR-ZA3100ES has 6/2 HDMI inputs/outputs versus 8/2 HDMI connectors of the Onkyo TX-RZ710. The HDMI Audio Return Channel (ARC) feature supports both devices. The HDMI eARC is available only on the STR-ZA3100ES. 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-RZ710 has a built-in phono stage for connecting a vinyl player.
Each of the AV receivers from our review supports 2 Multi-room zones. A voice control is not available. An ECO mode is only available for the TX-RZ710. The setup assistant will help you configure Sony STR-ZA3100ES.
Both devices have support for Dolby Atmos multichannel audio format. The surround sound technology DTS:X is supported by devices under review.