It makes sense comparing Yamaha RX-V671 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-V671 has 7.1 versus 9.2 for Onkyo TX-RZ630. Regarding power, then RX-V671 has such a W/Ohm ratio - 90/8, 150/4 when TX-RZ630 has a power of 90/8, 215/6. The THD is 0.09% for the RX-V671 but 0.08% for the TX-RZ630.
Characteristics of digital to analog converter (DAC) are different, Burr-Brown 192 KHz/24-bit for RX-V671 and AK4458 384 KHz/32-bit for the TX-RZ630. Both the RX-V671 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. Rivals from our review have Bluetooth support. Only the TX-RZ630 supports Spotify. The RX-V671 can work with the audio stream from Napster, and the TX-RZ630 can receive a content from Deezer, TIDAL, Pandora. 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-V671 can scale the input HDMI signal, unlike the TX-RZ630. Dolby Vision technology found support only on the TX-RZ630.
The Yamaha RX-V671 has 6/1 HDMI inputs/outputs versus 7/2 HDMI connectors of the Onkyo TX-RZ630. 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. These compared receivers have a built-in phono stage for connecting a vinyl player.
The RX-V671 supports 2 Multi-room zones, versus 3 for the TX-RZ630. An ECO mode is not present in each of the AV receivers. The setup assistant will help you configure Onkyo TX-RZ630.
Only the TX-RZ630 has a Dolby Atmos multichannel audio format support. A surround technology DTS:X is supported only by the TX-RZ630.