Having had an opportunity to test Marantz NR1508 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 - 5.2 versus 7.2, respectively, for devices. In terms of power, there are differences, the NR1508 has such a ratio W/Ohm - 50/8, while the TX-NR545 has a power of 100/6. A common feature for devices is the same total harmonic distortion - 0.08%.
The manufacturer installed different DACs, the NR1508 received the model 192 KHz/24-bit, but the TX-NR545 is equipped with Hi-Grade 384 KHz/32-bit. The Bi-amping function is implemented only in the Onkyo TX-NR545. Both Marantz NR1508 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 NR1508 works with Deezer, TIDAL, Pandora, 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 NR1508 and the TX-NR545. None of the devices can increase the resolution of the incoming video signal. Operation with the Dolby Vision is only possible with the NR1508.
The number of HDMI inputs/outputs is the same - 6/1. HDMI Audio Return Channel is only available on Onkyo TX-NR545. HDMI eARC is not supported by the NR1508 and the TX-NR545. When comparing receivers, it becomes clear that each of the rivals can work with HDMI CEC. NR1508 and TX-NR545 support the standard HDCP 2.2. Unlike most receivers, our models do not have a built-in phono stage for connecting a vinyl player. There is an ECO mode in NR1508. The Marantz NR1508 and the Onkyo TX-NR545 can be properly configured using the setup assistant.
A Dolby Atmos multichannel audio format is available only in the TX-NR545. A DTS:X surround technology is not supported by devices from our comparison.