Having had an opportunity to test Onkyo TX-NR555 vs Marantz NR1608, I’d like to share my impression here to facilitate your choice of a new AV receiver.
AV receivers under review have the same number of channels. In terms of power, there are differences, the TX-NR555 has such a ratio W/Ohm - 130/6, while the NR1608 has a power of 50/8, 70/6. The value of total harmonic distortion is also different, and for the TX-NR555 it is 0.08%, but for the NR1608 it is 0.05%.
The manufacturer installed different DACs, the TX-NR555 received the model Hi-Grade 384 KHz/32-bit, but the NR1608 is equipped with AK4458 384 KHz/32-bit. Each of the compared opponents supports Bi-amping. Both Onkyo TX-NR555 and Marantz NR1608 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 versus AirPlay, AirPlay 2 respectively. Access to the Spotify service is on each of the competitors. The number of available streaming services varies for receivers, the Onkyo TX-NR555 works with Deezer, TIDAL, Pandora, but the Marantz NR1608 works with Deezer, TIDAL, Pandora, Napster, SiriusXM, TuneIn Radio, iHeart Radio, Sound Cloud.
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 TX-NR555 and the NR1608. Video scaling is only possible with the NR1608. Operation with the Dolby Vision is only possible with the NR1608.
The number of HDMI inputs/outputs varies depending on the receiver, the TX-NR555 has 6/1, and the NR1608 has 8/1. HDMI Audio Return Channel is implemented in both devices. HDMI eARC is not supported by the TX-NR555 and the NR1608. When comparing receivers, it becomes clear that each of the rivals can work with HDMI CEC. TX-NR555 and NR1608 support the standard HDCP 2.2. In the presence of a built-in phono stage for connecting a vinyl player only at Onkyo TX-NR555.
Ability to create 2 Multi zones inherent in both AV receivers. There is an ECO mode in either AV receiver. The Marantz NR1608 can be properly configured using the setup assistant.
A Dolby Atmos multichannel audio format is available both models. A DTS:X surround technology is supported by devices from our comparison.