It makes sense comparing Denon AVR-S940H vs Onkyo TX-RZ630 because they both are able to give some premium features.
A significant difference between the receivers in the number of channels, Denon AVR-S940H has 7.2 versus 9.2 for Onkyo TX-RZ630. Regarding power, then AVR-S940H has such a W/Ohm ratio - 90/8, 125/6 when TX-RZ630 has a power of 90/8, 215/6. The THD is the same and is 0.08%.
Characteristics of digital to analog converter (DAC) are different, 192 KHz/32-bit for AVR-S940H and AK4458 384 KHz/32-bit for the TX-RZ630. Only the TX-RZ630 supports Bi-amping feature. 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 Denon AVR-S940H has support for AirPlay, AirPlay 2, and its competitor in our comparison - AirPlay. Spotify can be used on each receiver. The AVR-S940H can work with the audio stream from Deezer, TIDAL, Pandora, Napster, SiriusXM, TuneIn Radio, iHeart Radio, Sound Cloud, and the TX-RZ630 can receive a content from Deezer, TIDAL, Pandora.
Both AV receivers support HDR10 technology (High dynamic range). 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 AVR-S940H can scale the input HDMI signal, unlike the TX-RZ630. The HDR standard - Dolby Vision is supported by these receivers.
The Denon AVR-S940H has 8/2 HDMI inputs/outputs versus 7/2 HDMI connectors of the Onkyo TX-RZ630. 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.
The AVR-S940H supports 2 Multi-room zones, versus 3 for the TX-RZ630. The AVR-S940H supports voice control via Amazon Alexa, Google Assistant, Siri, Josh.AI, and the TX-RZ630 - Google Assistant. An ECO mode is only available for the AVR-S940H. Both AVR-S940H and TX-RZ630 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.