Having had an opportunity to test Onkyo TX-NR555 vs Denon AVR-X2500H, 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 AVR-X2500H has a power of 95/8, 125/6. A common feature for devices is the same total harmonic distortion - 0.08%.
The manufacturer installed different DACs, the TX-NR555 received the model Hi-Grade 384 KHz/32-bit, but the AVR-X2500H is equipped with AK4490 384 KHz/32-bit. Each of the compared opponents supports Bi-amping. Both Onkyo TX-NR555 and Denon AVR-X2500H can transmit an audio signal directly to the amplifier and bypasses any DSP processing. 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-X2500H works with Deezer, TIDAL, Pandora, Napster, SiriusXM, TuneIn Radio, iHeart Radio, Sound Cloud. 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 AVR-X2500H. None of the devices can increase the resolution of the incoming video signal. Operation with the Dolby Vision is only possible with the AVR-X2500H.
The number of HDMI inputs/outputs varies depending on the receiver, the TX-NR555 has 6/1, and the AVR-X2500H has 8/2. HDMI Audio Return Channel is implemented in both devices. HDMI eARC is not supported by the TX-NR555 and the AVR-X2500H. When comparing receivers, it becomes clear that each of the rivals can work with HDMI CEC. TX-NR555 and AVR-X2500H support the standard HDCP 2.2. 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-X2500H 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.