An affordable AV receiver is always a good option to consider, so Marantz NR1509 vs Pioneer VSX-S520 comparison definitely makes sense.
A significant difference between the receivers in the number of channels, Marantz NR1509 has 5.2 versus 5.1 for Pioneer VSX-S520. Regarding power, then NR1509 has such a W/Ohm ratio - 50/8, 60/6 when VSX-S520 has a power of 50/4. The THD is 0.08% for the NR1509 but 0.09% for the VSX-S520.
Competitors' digital to analog converter (DAC) is identical to 192 KHz/24-bit. 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.
WI-FI modules have the same characteristics: 2.4/5GHz. Rivals from our review have Bluetooth support. The Marantz NR1509 has support for AirPlay, AirPlay 2, and its competitor in our comparison - AirPlay. Spotify can be used on each receiver. The NR1509 can work with the audio stream from Deezer, Pandora, TuneIn Radio, 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 NR1509. The HDR standard - Dolby Vision is supported by these receivers.
The Marantz NR1509 has 7/1 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. An ECO mode is only available for the NR1509. Both NR1509 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.