The Onkyo TX-RZ840 vs Marantz SR6012 comparison proves that these receivers have many common features.
Considered AV receivers have the same number of channels 9.2. Regarding power, then TX-RZ840 has such a W/Ohm ratio - 180/6 when SR6012 has a power of 110/8, 150/6. The THD is the same and is 0.08%.
Characteristics of digital to analog converter (DAC) are different, AKM 384 KHz/32-bit for TX-RZ840 and 192 KHz/32-bit for the SR6012. Both the TX-RZ840 and the SR6012 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 Apple Music service is implemented on considered devices: AirPlay, AirPlay 2. Spotify can be used on each receiver. The TX-RZ840 can work with the audio stream from Deezer, TIDAL, Pandora, TuneIn Radio, and the SR6012 can receive a content from Deezer, TIDAL, Pandora, Napster, SiriusXM, TuneIn Radio, iHeart Radio, Sound Cloud. 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 SR6012 can scale the input HDMI signal, unlike the TX-RZ840. The HDR standard - Dolby Vision is supported by these receivers.
The Onkyo TX-RZ840 has 7/2 HDMI inputs/outputs versus 8/3 HDMI connectors of the Marantz SR6012. The HDMI Audio Return Channel (ARC) feature supports both devices. HDMI eARC is available in each model. 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 TX-RZ840 supports 3 Multi-room zones, versus 2 for the SR6012. The TX-RZ840 supports voice control via Google Assistant, and the SR6012 - Amazon Alexa, Google Assistant, Siri, Josh.AI. An ECO mode is only available for the SR6012. Both TX-RZ840 and SR6012 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.