It makes sense comparing Yamaha RX-V671 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, Yamaha RX-V671 has 7.1 versus 7.2 for Onkyo TX-NR595. Regarding power, then RX-V671 has such a W/Ohm ratio - 90/8, 150/4 when TX-NR595 has a power of 80/8, 170/6. The THD is 0.09% for the RX-V671 but 0.08% for the TX-NR595.
Characteristics of digital to analog converter (DAC) are different, Burr-Brown 192 KHz/24-bit for RX-V671 and AKM 384 KHz/32-bit for the TX-NR595. Both the RX-V671 and the TX-NR595 support Bi-amping. 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. The RX-V671 can work with the audio stream from Napster, and the TX-NR595 can receive a content from Deezer, TIDAL, Pandora, TuneIn Radio. 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 rivals can scale the resolution of the incoming HDMI signal. Dolby Vision technology found support only on the TX-NR595.
The Yamaha RX-V671 has 6/1 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. These compared receivers have a built-in phono stage for connecting a vinyl player.
Each of the AV receivers from our review supports 2 Multi-room zones. 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.