It makes sense comparing Marantz AV7703 vs Onkyo TX-8260 because they both are able to give some premium features.
A significant difference between the receivers in the number of channels, Marantz AV7703 has 11.2 versus 2.0 for Onkyo TX-8260. The THD is 0.08% for the AV7703 but 0.09% for the TX-8260.
Characteristics of digital to analog converter (DAC) are different, 192 KHz/32-bit for AV7703 and AK4452 384 KHz/32-bit for the TX-8260. Only the AV7703 supports Bi-amping feature. The Marantz AV7703 can transmit an audio signal directly to the amplifier and bypasses any DSP processing. Rivals from our review have Bluetooth support. The Marantz AV7703 has support for AirPlay, AirPlay 2, and its competitor in our comparison - AirPlay. Spotify can be used on each receiver. The AV7703 can work with the audio stream from Deezer, TIDAL, Pandora, Napster, iHeart Radio, SiriusXM, Sound Cloud, and the TX-8260 can receive a content from TIDAL, Pandora, TuneIn Radio.
Only the Marantz AV7703 has support for High dynamic range (HDR). Only the AV7703 provides HDMI signal transmission in standby mode. The AV7703 can scale the input HDMI signal, unlike the TX-8260. Dolby Vision technology found support only on the AV7703. Only the AV7703 supports HDMI Audio Return Channel (ARC). Unfortunately, HDMI eARC is not available on monitored devices. Of the two receivers in our comparison, HDMI CEC is present in only the AV7703. These compared receivers have a built-in phono stage for connecting a vinyl player.
The AV7703 supports 3 Multi-room zones, versus 2 for the TX-8260. An ECO mode is only available for the AV7703. The setup assistant will help you configure Marantz AV7703.
Only the AV7703 has a Dolby Atmos multichannel audio format support. A surround technology DTS:X is supported only by the AV7703.