It makes sense comparing Pioneer Elite SC-LX704 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, Pioneer Elite SC-LX704 has 9.2 versus 11.2 for Denon AVR-X4400H. Regarding power, then Elite SC-LX704 has such a W/Ohm ratio - 135/8 when AVR-X4400H has a power of 125/8, 165/6. The THD is 0.08% for the Elite SC-LX704 but 0.05% for the AVR-X4400H.
Characteristics of digital to analog converter (DAC) are different, ES9026PRO 384 KHz/32-bit for Elite SC-LX704 and AK4458 384 KHz/32-bit for the AVR-X4400H. Both the Elite SC-LX704 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 Apple Music service is implemented on considered devices: AirPlay, AirPlay 2. Spotify can be used on each receiver. The Elite SC-LX704 can work with the audio stream from Deezer, TIDAL, Pandora, and the AVR-X4400H can receive a content from Deezer, TIDAL, Pandora, Napster, SiriusXM, TuneIn Radio, iHeart Radio, Sound Cloud. 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 Pioneer Elite SC-LX704 has 7/3 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. The Elite SC-LX704 supports the protection of digital content of the standard HDCP 2.3, versus HDCP 2.2 in the AVR-X4400H. These compared receivers have a built-in phono stage for connecting a vinyl player.
Each of the AV receivers from our review supports 3 Multi-room zones. The Elite SC-LX704 supports voice control via Amazon Alexa, and the AVR-X4400H - Amazon Alexa, Google Assistant, Siri, Josh.AI. An ECO mode is only available for the AVR-X4400H. Both Elite SC-LX704 and AVR-X4400H can be configured using the Setup assistant.
Both devices have support for Dolby Atmos multichannel audio format. The surround sound technology DTS:X is supported by devices under review.