It makes sense comparing Marantz SR6014 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, Marantz SR6014 has 9.2 versus 7.1 for Yamaha RX-V671. Regarding power, then SR6014 has such a W/Ohm ratio - 110/8, 185/6 when RX-V671 has a power of 90/8, 150/4. The THD is 0.08% for the SR6014 but 0.09% for the RX-V671.
Characteristics of digital to analog converter (DAC) are different, AK4458 384 KHz/32-bit for SR6014 and Burr-Brown 192 KHz/24-bit for the RX-V671. Both the SR6014 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 SR6014 supports Spotify. The SR6014 can work with the audio stream from Deezer, TIDAL, Pandora, TuneIn Radio, iHeart 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. Both rivals can scale the resolution of the incoming HDMI signal. Dolby Vision technology found support only on the SR6014.
The Marantz SR6014 has 8/3 HDMI inputs/outputs versus 6/1 HDMI connectors of the Yamaha RX-V671. The HDMI Audio Return Channel (ARC) feature supports both devices. The HDMI eARC is available only on the SR6014. The Consumer Electronics Control (CEC) feature is present in most modern AV receivers and the models in our comparison are no exception. The SR6014 supports the protection of digital content of the standard HDCP 2.3, versus HDCP 2.2 in the RX-V671. 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 only available for the SR6014. The setup assistant will help you configure Marantz SR6014.
Only the SR6014 has a Dolby Atmos multichannel audio format support. A surround technology DTS:X is supported only by the SR6014.