It makes sense comparing Denon AVR-X6500H 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, Denon AVR-X6500H has 11.2 versus 7.1 for Yamaha RX-V671. Regarding power, then AVR-X6500H has such a W/Ohm ratio - 140/8, 175/6 when RX-V671 has a power of 90/8, 150/4. The THD is 0.05% for the AVR-X6500H but 0.09% for the RX-V671.
Characteristics of digital to analog converter (DAC) are different, 192 KHz/32-bit for AVR-X6500H and Burr-Brown 192 KHz/24-bit for the RX-V671. Both the AVR-X6500H 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.
Only the Denon AVR-X6500H can connect to the Internet via WI-FI. Rivals from our review have Bluetooth support. Only the AVR-X6500H supports Spotify. The AVR-X6500H can work with the audio stream from Deezer, TIDAL, Pandora, Napster, SiriusXM, TuneIn Radio, iHeart Radio, Sound Cloud, Mood Mix, 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 AVR-X6500H.
The Denon AVR-X6500H 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 AVR-X6500H. 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 AVR-X6500H supports 3 Multi-room zones, versus 2 for the RX-V671. An ECO mode is only available for the AVR-X6500H. The setup assistant will help you configure Denon AVR-X6500H.
Only the AVR-X6500H has a Dolby Atmos multichannel audio format support. A surround technology DTS:X is supported only by the AVR-X6500H.