An affordable AV receiver is always a good option to consider, so Denon AVR-S650H vs Pioneer VSX-S520 comparison definitely makes sense.
A significant difference between the receivers in the number of channels, Denon AVR-S650H has 5.2 versus 5.1 for Pioneer VSX-S520. Regarding power, then AVR-S650H has such a W/Ohm ratio - 75/8, 100/6 when VSX-S520 has a power of 50/4. The THD is 0.08% for the AVR-S650H but 0.09% for the VSX-S520.
Characteristics of digital to analog converter (DAC) are different, AKM 192 KHz/32-bit for AVR-S650H and 192 KHz/24-bit for the VSX-S520. None of the models 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 Denon AVR-S650H has support for AirPlay, AirPlay 2, and its competitor in our comparison - AirPlay. Spotify can be used on each receiver. The AVR-S650H can work with the audio stream from Deezer, TIDAL, Pandora, Napster, SiriusXM, TuneIn Radio, iHeart Radio, Sound Cloud, Mood Mix, and the VSX-S520 can receive a content from Deezer, TIDAL, TuneIn Radio. 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 AVR-S650H. The HDR standard - Dolby Vision is supported by these receivers.
The Denon AVR-S650H has 5/1 HDMI inputs/outputs versus 4/1 HDMI connectors of the Pioneer VSX-S520. The HDMI Audio Return Channel (ARC) feature supports both devices. The HDMI eARC is available only on the AVR-S650H. The Consumer Electronics Control (CEC) feature is present in most modern AV receivers and the models in our comparison are no exception. The AVR-S650H supports the protection of digital content of the standard HDCP 2.3, versus HDCP 2.2 in the VSX-S520. These compared receivers have a built-in phono stage for connecting a vinyl player. An ECO mode is only available for the AVR-S650H. Both AVR-S650H and VSX-S520 can be configured using the Setup assistant.
Only the VSX-S520 has a Dolby Atmos multichannel audio format support. A surround technology DTS:X is supported only by the VSX-S520.