It makes sense comparing Pioneer VSX-S520 vs Yamaha RX-V683BL because they both are able to give some premium features.
A significant difference between the receivers in the number of channels, Pioneer VSX-S520 has 5.1 versus 7.2 for Yamaha RX-V683BL. Regarding power, then VSX-S520 has such a W/Ohm ratio - 50/4 when RX-V683BL has a power of 90/8, 150/4. The THD is 0.09% for the VSX-S520 but 0.06% for the RX-V683BL.
Characteristics of digital to analog converter (DAC) are different, 192 KHz/24-bit for VSX-S520 and Burr-Brown 192 KHz/24-bit for the RX-V683BL. Only the RX-V683BL supports Bi-amping feature. 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 Apple Music service is implemented on considered devices: AirPlay. Spotify can be used on each receiver. The VSX-S520 can work with the audio stream from Deezer, TIDAL, TuneIn Radio, and the RX-V683BL can receive a content from Pandora, Sirius XM, Napster, JUKE, Qobuz. 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 rivals can scale the resolution of the incoming HDMI signal. The HDR standard - Dolby Vision is supported by these receivers.
The Pioneer VSX-S520 has 4/1 HDMI inputs/outputs versus 6/1 HDMI connectors of the Yamaha RX-V683BL. 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 RX-V683BL. Both VSX-S520 and RX-V683BL can be configured using the Setup assistant.
Both devices have support for Dolby Atmos multichannel audio format. The surround sound technology DTS:X is supported by devices under review.