It makes sense comparing Onkyo TX-NR575 vs Yamaha RX-V671 because they both are able to give some premium features.
A significant difference between the receivers in the number of channels, Onkyo TX-NR575 has 7.2 versus 7.1 for Yamaha RX-V671. Regarding power, then TX-NR575 has such a W/Ohm ratio - 135/6 when RX-V671 has a power of 90/8, 150/4. The THD is 0.08% for the TX-NR575 but 0.09% for the RX-V671.
Characteristics of digital to analog converter (DAC) are different, 384 KHz/32-bit for TX-NR575 and Burr-Brown 192 KHz/24-bit for the RX-V671. Both the TX-NR575 and the RX-V671 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-NR575 supports Spotify. The TX-NR575 can work with the audio stream from Deezer, TIDAL, Pandora, TuneIn Radio, and the RX-V671 can receive a content from Napster. 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-NR575. Dolby Vision technology found support only on the TX-NR575.
The Onkyo TX-NR575 has 4/1 HDMI inputs/outputs versus 6/1 HDMI connectors of the Yamaha RX-V671. 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. A voice control is not available. An ECO mode is not present in each of the AV receivers. The setup assistant will help you configure Onkyo TX-NR575.
Only the TX-NR575 has a Dolby Atmos multichannel audio format support. A surround technology DTS:X is supported only by the TX-NR575.