An affordable AV receiver is always a good option to consider, so Onkyo TX-NR555 vs Pioneer VSX-S520 comparison definitely makes sense.
A significant difference between the receivers in the number of channels, Onkyo TX-NR555 has 7.2 versus 5.1 for Pioneer VSX-S520. Regarding power, then TX-NR555 has such a W/Ohm ratio - 130/6 when VSX-S520 has a power of 50/4. The THD is 0.08% for the TX-NR555 but 0.09% for the VSX-S520.
Characteristics of digital to analog converter (DAC) are different, Hi-Grade 384 KHz/32-bit for TX-NR555 and 192 KHz/24-bit for the VSX-S520. 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.
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-NR555 can work with the audio stream from Deezer, TIDAL, Pandora, and the VSX-S520 can receive a content from Deezer, TIDAL, TuneIn Radio.
These units support HDR technology. 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 VSX-S520 can scale the input HDMI signal, unlike the TX-NR555. Dolby Vision technology found support only on the VSX-S520.
The Onkyo TX-NR555 has 6/1 HDMI inputs/outputs versus 4/1 HDMI connectors of the Pioneer VSX-S520. 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. A voice control is not available. An ECO mode is only available for the TX-NR555. The setup assistant will help you configure Pioneer VSX-S520.
Both devices have support for Dolby Atmos multichannel audio format. The surround sound technology DTS:X is supported by devices under review.