An affordable AV receiver is always a good option to consider, so Denon AVR-S650H vs Onkyo TX-NR555 comparison definitely makes sense.
A significant difference between the receivers in the number of channels, Denon AVR-S650H has 5.2 versus 7.2 for Onkyo TX-NR555. Regarding power, then AVR-S650H has such a W/Ohm ratio - 75/8, 100/6 when TX-NR555 has a power of 130/6. The THD is the same and is 0.08%.
Characteristics of digital to analog converter (DAC) are different, AKM 192 KHz/32-bit for AVR-S650H and Hi-Grade 384 KHz/32-bit for the TX-NR555. Only the TX-NR555 supports Bi-amping feature. Each of the AV receivers can transmit an audio signal directly to the amplifier and bypasses any DSP processing. Rivals from our review have Bluetooth support. The Denon AVR-S650H has support for AirPlay, AirPlay 2, and its competitor in our comparison - AirPlay. Spotify can be used on each receiver. The AVR-S650H can work with the audio stream from Deezer, TIDAL, Pandora, Napster, SiriusXM, TuneIn Radio, iHeart Radio, Sound Cloud, Mood Mix, and the TX-NR555 can receive a content from Deezer, TIDAL, Pandora. Compared AV receivers retain the quality of 4K/60Hz signal when transmitting from a source to a TV or projector. HDMI signal transmission in standby mode is implemented in each of the devices. Both competitors are not able to scale the HDMI signal. Dolby Vision technology found support only on the AVR-S650H.
The Denon AVR-S650H has 5/1 HDMI inputs/outputs versus 6/1 HDMI connectors of the Onkyo TX-NR555. The HDMI Audio Return Channel (ARC) feature supports both devices. The HDMI eARC is available only on the AVR-S650H. The Consumer Electronics Control (CEC) feature is present in most modern AV receivers and the models in our comparison are no exception. The AVR-S650H supports the protection of digital content of the standard HDCP 2.3, versus HDCP 2.2 in the TX-NR555. These compared receivers have a built-in phono stage for connecting a vinyl player. It is also worth noting that the ECO mode is presented in each of the receivers. The setup assistant will help you configure Denon AVR-S650H.
Only the TX-NR555 has a Dolby Atmos multichannel audio format support. A surround technology DTS:X is supported only by the TX-NR555.