Having had an opportunity to test Onkyo TX-NR555 vs Denon AVR-X3700H, 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 - 7.2 versus 9.2, respectively, for devices. In terms of power, there are differences, the TX-NR555 has such a ratio W/Ohm - 130/6, while the AVR-X3700H has a power of 105/8, 135/6. A common feature for devices is the same total harmonic distortion - 0.08%. Each of the compared opponents supports Bi-amping. Both Onkyo TX-NR555 and Denon AVR-X3700H 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 Denon AVR-X3700H works with Deezer, TIDAL, Pandora, SiriusXM, Qobuz, TuneIn Radio. Signaling over HDMI in standby mode can provide the TX-NR555 and the AVR-X3700H. Video scaling is only possible with the AVR-X3700H. Operation with the Dolby Vision is only possible with the AVR-X3700H.
The number of HDMI inputs/outputs varies depending on the receiver, the TX-NR555 has 6/1, and the AVR-X3700H has 7/3. HDMI Audio Return Channel is implemented in both devices. HDMI eARC is only supported by the AVR-X3700H. When comparing receivers, it becomes clear that each of the rivals can work with HDMI CEC. The TX-NR555 has support for the standard HDCP 2.2, compared to the AVR-X3700H, which supports the standard HDCP 2.3. Like most receivers, our models have a built-in phono stage for connecting a vinyl player.
Ability to create 2 Multi zones inherent in both AV receivers. There is an ECO mode in either AV receiver. The Denon AVR-X3700H 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.