Having had an opportunity to test Marantz AV7703 vs Onkyo TX-NR545, I’d like to share my impression here to facilitate your choice of a new AV receiver.
The number of channels for receivers is different - 11.2 versus 7.2, respectively, for devices. A common feature for devices is the same total harmonic distortion - 0.08%.
The manufacturer installed different DACs, the AV7703 received the model 192 KHz/32-bit, but the TX-NR545 is equipped with Hi-Grade 384 KHz/32-bit. Each of the compared opponents supports Bi-amping. Both Marantz AV7703 and Onkyo TX-NR545 can transmit an audio signal directly to the amplifier and bypasses any DSP processing.
These units have the same Wi-Fi modules. Each of the receivers has a Bluetooth connector. The contenders have differences in the supported services from Apple - AirPlay, AirPlay 2 versus AirPlay respectively. Access to the Spotify service is on each of the competitors. The number of available streaming services varies for receivers, the Marantz AV7703 works with Deezer, TIDAL, Pandora, Napster, iHeart Radio, SiriusXM, Sound Cloud, but the Onkyo TX-NR545 works with Tunein Radio.
Support for the HDR function can only boast of each of the AV receivers. The quality of 4K/60Hz signal remains unchanged when transmitting from a source to a TV or projector via HDMI for both receivers. Signaling over HDMI in standby mode can provide the AV7703 and the TX-NR545. Video scaling is only possible with the AV7703. Operation with the Dolby Vision is only possible with the AV7703.
The number of HDMI inputs/outputs varies depending on the receiver, the AV7703 has 8/3, and the TX-NR545 has 6/1. HDMI Audio Return Channel is implemented in both devices. HDMI eARC is not supported by the AV7703 and the TX-NR545. When comparing receivers, it becomes clear that each of the rivals can work with HDMI CEC. AV7703 and TX-NR545 support the standard HDCP 2.2. In the presence of a built-in phono stage for connecting a vinyl player only at Marantz AV7703.
Unlike the AV7703 where 3 Multi zones is provided, the TX-NR545 works with 2 Multi zones. There is an ECO mode in AV7703. The Marantz AV7703 and the Onkyo TX-NR545 can be properly configured using the setup assistant.
A Dolby Atmos multichannel audio format is available both models. Only in the AV7703 realized a DTS:X surround technology.