It makes sense comparing Onkyo TX-NR555 vs Yamaha RX-V485 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 5.1 for Yamaha RX-V485. Regarding power, then TX-NR555 has such a W/Ohm ratio - 130/6 when RX-V485 has a power of 80/8, 145/6. The THD is 0.08% for the TX-NR555 but 0.09% for the RX-V485.
Characteristics of digital to analog converter (DAC) are different, Hi-Grade 384 KHz/32-bit for TX-NR555 and Burr-Brown 384 KHz/32-bit for the RX-V485. Both the TX-NR555 and the RX-V485 support Bi-amping. 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 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 RX-V485 can receive a content from Deezer, TIDAL, Pandora, Napster, SiriusXM. 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 RX-V485 can scale the input HDMI signal, unlike the TX-NR555. Dolby Vision technology found support only on the RX-V485.
The Onkyo TX-NR555 has 6/1 HDMI inputs/outputs versus 4/1 HDMI connectors of the Yamaha RX-V485. The HDMI Audio Return Channel (ARC) feature supports both devices. The HDMI eARC is available only on the RX-V485. 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 RX-V485. The TX-NR555 has a built-in phono stage for connecting a vinyl player.
Each of the AV receivers from our review supports 2 Multi-room zones. It is also worth noting that the ECO mode is presented in each of the receivers. The setup assistant will help you configure Yamaha RX-V485.
Only the TX-NR555 has a Dolby Atmos multichannel audio format support. A surround technology DTS:X is supported only by the TX-NR555.