It makes sense comparing Marantz NR1504 vs Onkyo TX-RZ710 because they both are able to give some premium features.
A significant difference between the receivers in the number of channels, Marantz NR1504 has 5.1 versus 7.2 for Onkyo TX-RZ710. Regarding power, then NR1504 has such a W/Ohm ratio - 50/8, 60/6 when TX-RZ710 has a power of 175/6. The THD is the same and is 0.08%.
Characteristics of digital to analog converter (DAC) are different, 192 KHz/24-bit for NR1504 and AK4458 384 KHz/32-bit for the TX-RZ710. Only the TX-RZ710 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 Apple Music service is implemented on considered devices: AirPlay. Spotify can be used on each receiver. The NR1504 can work with the audio stream from Pandora, SiriusXM, and the TX-RZ710 can receive a content from Deezer, TIDAL, Pandora, Tunein Radio.
Only the Onkyo TX-RZ710 has support for High dynamic range (HDR). HDMI signal transmission in standby mode is implemented in each of the devices. The TX-RZ710 can scale the input HDMI signal, unlike the NR1504. The HDR standard - Dolby Vision is not supported by these receivers.
The Marantz NR1504 has 6/1 HDMI inputs/outputs versus 8/2 HDMI connectors of the Onkyo TX-RZ710. 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. The TX-RZ710 has a built-in phono stage for connecting a vinyl player. A voice control is not available. An ECO mode is only available for the TX-RZ710. The setup assistant will help you configure Marantz NR1504.
Only the TX-RZ710 has a Dolby Atmos multichannel audio format support. A surround technology DTS:X is supported only by the TX-RZ710.