It makes sense comparing Yamaha RX-V685BL vs Onkyo TX-RZ630 because they both are able to give some premium features.
A significant difference between the receivers in the number of channels, Yamaha RX-V685BL has 7.2 versus 9.2 for Onkyo TX-RZ630. Regarding power, then RX-V685BL has such a W/Ohm ratio - 90/8, 150/4 when TX-RZ630 has a power of 90/8, 215/6. The THD is 0.06% for the RX-V685BL but 0.08% for the TX-RZ630.
Characteristics of digital to analog converter (DAC) are different, Burr-Brown 384 KHz/32-bit for RX-V685BL and AK4458 384 KHz/32-bit for the TX-RZ630. Both the RX-V685BL and the TX-RZ630 support Bi-amping. Each of the AV receivers can transmit an audio signal directly to the amplifier and bypasses any DSP processing.
WI-FI modules have the same characteristics: 2.4/5GHz. Rivals from our review have Bluetooth support. The Apple Music service is implemented on considered devices: AirPlay. Only the TX-RZ630 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 RX-V685BL can scale the input HDMI signal, unlike the TX-RZ630. The HDR standard - Dolby Vision is supported by these receivers.
The Yamaha RX-V685BL has 5/2 HDMI inputs/outputs versus 7/2 HDMI connectors of the Onkyo TX-RZ630. The HDMI Audio Return Channel (ARC) feature supports both devices. The HDMI eARC is available only on the RX-V685BL. 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. These compared receivers have a built-in phono stage for connecting a vinyl player.
The RX-V685BL supports 2 Multi-room zones, versus 3 for the TX-RZ630. An ECO mode is only available for the RX-V685BL. Both RX-V685BL and TX-RZ630 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.