An affordable AV receiver is always a good option to consider, so Onkyo TX-RZ820 vs Onkyo TX-NR555 comparison definitely makes sense.
Considered AV receivers have the same number of channels 7.2. Regarding power, then TX-RZ820 has such a W/Ohm ratio - 160/8 when TX-NR555 has a power of 130/6. The THD is the same and is 0.08%.
Characteristics of digital to analog converter (DAC) are different, AK4458 384 KHz/32-bit for TX-RZ820 and Hi-Grade 384 KHz/32-bit for the TX-NR555. Both the TX-RZ820 and the TX-NR555 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 Apple Music service is implemented on considered devices: AirPlay. Spotify can be used on each receiver. The TX-RZ820 can work with the audio stream from Deezer, TIDAL, and the TX-NR555 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. Both competitors are not able to scale the HDMI signal. Dolby Vision technology found support only on the TX-RZ820.
The Onkyo TX-RZ820 has 7/2 HDMI inputs/outputs versus 6/1 HDMI connectors of the Onkyo TX-NR555. 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.
Each of the AV receivers from our review supports 2 Multi-room zones. A voice control is not available. It is also worth noting that the ECO mode is presented in each of the receivers. The setup assistant will help you configure Onkyo TX-RZ820.
Both devices have support for Dolby Atmos multichannel audio format. The surround sound technology DTS:X is supported by devices under review.