It makes sense comparing Yamaha RX-V675 vs Denon AVR-X4400H because they both are able to give some premium features.
A significant difference between the receivers in the number of channels, Yamaha RX-V675 has 7.2 versus 11.2 for Denon AVR-X4400H. Regarding power, then RX-V675 has such a W/Ohm ratio - 90/8, 150/4 when AVR-X4400H has a power of 125/8, 165/6. The THD is 0.09% for the RX-V675 but 0.05% for the AVR-X4400H.
Characteristics of digital to analog converter (DAC) are different, Burr-Brown 192 KHz/24-bit for RX-V675 and AK4458 384 KHz/32-bit for the AVR-X4400H. Both the RX-V675 and the AVR-X4400H 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. The Yamaha RX-V675 has support for AirPlay, and its competitor in our comparison - AirPlay, AirPlay 2. Spotify can be used on each receiver. The RX-V675 can work with the audio stream from Napster, and the AVR-X4400H can receive a content from Deezer, TIDAL, Pandora, Napster, SiriusXM, TuneIn Radio, iHeart Radio, Sound Cloud.
Only the Denon AVR-X4400H has support for High dynamic range (HDR). 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. The HDR standard - Dolby Vision is supported by these receivers.
The Yamaha RX-V675 has 6/1 HDMI inputs/outputs versus 8/3 HDMI connectors of the Denon AVR-X4400H. The HDMI Audio Return Channel (ARC) feature supports both devices. The HDMI eARC is available only on the AVR-X4400H. 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. The AVR-X4400H has a built-in phono stage for connecting a vinyl player.
The RX-V675 supports 2 Multi-room zones, versus 3 for the AVR-X4400H. It is also worth noting that the ECO mode is presented in each of the receivers. The setup assistant will help you configure Denon AVR-X4400H.
Only the AVR-X4400H has a Dolby Atmos multichannel audio format support. A surround technology DTS:X is supported only by the AVR-X4400H.