An affordable AV receiver is always a good option to consider, so Yamaha RX-V377 vs Onkyo TX-NR555 comparison definitely makes sense.
A significant difference between the receivers in the number of channels, Yamaha RX-V377 has 5.1 versus 7.2 for Onkyo TX-NR555. Regarding power, then RX-V377 has such a W/Ohm ratio - 100/8, 135/6 when TX-NR555 has a power of 130/6. The THD is 0.09% for the RX-V377 but 0.08% for the TX-NR555.
Characteristics of digital to analog converter (DAC) are different, Burr-Brown 192 KHz/24-bit for RX-V377 and Hi-Grade 384 KHz/32-bit for the TX-NR555. Only the TX-NR555 supports Bi-amping feature. Each of the AV receivers can transmit an audio signal directly to the amplifier and bypasses any DSP processing. Only the TX-NR555 has Bluetooth support. Only the TX-NR555 supports Spotify.
Only the Onkyo TX-NR555 has support for High dynamic range (HDR). 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. The HDR standard - Dolby Vision is not supported by these receivers.
The Yamaha RX-V377 has 4/1 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. The TX-NR555 has a built-in phono stage for connecting a vinyl player. 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 Yamaha RX-V377.
Only the TX-NR555 has a Dolby Atmos multichannel audio format support. A surround technology DTS:X is supported only by the TX-NR555.