The Marantz SR6012 vs Pioneer VSX-LX503 comparison proves that these receivers have many common features.
Considered AV receivers have the same number of channels 9.2. Regarding power, then SR6012 has such a W/Ohm ratio - 110/8, 150/6 when VSX-LX503 has a power of 120/8, 230/6. The THD is the same and is 0.08%.
Characteristics of digital to analog converter (DAC) are different, 192 KHz/32-bit for SR6012 and AK4458 384 KHz/32-bit for the VSX-LX503. Both the SR6012 and the VSX-LX503 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 SR6012 has support for AirPlay, AirPlay 2, and its competitor in our comparison - AirPlay. Spotify can be used on each receiver. The SR6012 can work with the audio stream from Deezer, TIDAL, Pandora, Napster, SiriusXM, TuneIn Radio, iHeart Radio, Sound Cloud, and the VSX-LX503 can receive a content from Deezer, TIDAL, Pandora, 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. Both rivals can scale the resolution of the incoming HDMI signal. The HDR standard - Dolby Vision is supported by these receivers.
The Marantz SR6012 has 8/3 HDMI inputs/outputs versus 7/2 HDMI connectors of the Pioneer VSX-LX503. The HDMI Audio Return Channel (ARC) feature supports both devices. The HDMI eARC is available only on the SR6012. 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.
The SR6012 supports 2 Multi-room zones, versus 3 for the VSX-LX503. The SR6012 supports voice control via Amazon Alexa, Google Assistant, Siri, Josh.AI, and the VSX-LX503 - Google Assistant. An ECO mode is only available for the SR6012. Both SR6012 and VSX-LX503 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.