It makes sense comparing Marantz NR1609 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, Marantz NR1609 has 7.2 versus 9.2 for Onkyo TX-RZ630. Regarding power, then NR1609 has such a W/Ohm ratio - 50/8, 70/6 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/24-bit for NR1609 and AK4458 384 KHz/32-bit for the TX-RZ630. Both the NR1609 and the TX-RZ630 support Bi-amping. Each of the AV receivers can transmit an audio signal directly to the amplifier and bypasses any DSP processing.
WI-FI modules have the same characteristics: 2.4/5GHz. Rivals from our review have Bluetooth support. The Marantz NR1609 has support for AirPlay, AirPlay 2, and its competitor in our comparison - AirPlay. Spotify can be used on each receiver. The NR1609 can work with the audio stream from Deezer, Pandora, TuneIn Radio, and the TX-RZ630 can receive a content from Deezer, TIDAL, Pandora. 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 NR1609 can scale the input HDMI signal, unlike the TX-RZ630. The HDR standard - Dolby Vision is supported by these receivers.
The Marantz NR1609 has 8/1 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 NR1609 supports 2 Multi-room zones, versus 3 for the TX-RZ630. The NR1609 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 NR1609. Both NR1609 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.