It makes sense comparing Onkyo TX-NR555 vs Marantz SR7015 because they both are able to give some premium features.
A significant difference between the receivers in the number of channels, Onkyo TX-NR555 has 7.2 versus 9.2 for Marantz SR7015. Regarding power, then TX-NR555 has such a W/Ohm ratio - 130/6 when SR7015 has a power of 125/8, 165/6. The THD is 0.08% for the TX-NR555 but 0.05% for the SR7015. Both the TX-NR555 and the SR7015 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 Onkyo TX-NR555 has support for AirPlay, and its competitor in our comparison - AirPlay, AirPlay 2. Spotify can be used on each receiver. The TX-NR555 can work with the audio stream from Deezer, TIDAL, Pandora, and the SR7015 can receive a content from Deezer, TIDAL, Pandora, SiriusXM, Napster, SoundCloud. HDMI signal transmission in standby mode is implemented in each of the devices. The SR7015 can scale the input HDMI signal, unlike the TX-NR555. Dolby Vision technology found support only on the SR7015.
The Onkyo TX-NR555 has 6/1 HDMI inputs/outputs versus 8/3 HDMI connectors of the Marantz SR7015. The HDMI Audio Return Channel (ARC) feature supports both devices. The HDMI eARC is available only on the SR7015. The Consumer Electronics Control (CEC) feature is present in most modern AV receivers and the models in our comparison are no exception. The TX-NR555 supports the protection of digital content of the standard HDCP 2.2, versus HDCP 2.3 in the SR7015. These compared receivers have a built-in phono stage for connecting a vinyl player.
The TX-NR555 supports 2 Multi-room zones, versus 3 for the SR7015. It is also worth noting that the ECO mode is presented in each of the receivers. The setup assistant will help you configure Marantz SR7015.
Both devices have support for Dolby Atmos multichannel audio format. The surround sound technology DTS:X is supported by devices under review.