It makes sense comparing Onkyo TX-NR555 vs Denon AVR-S950H because they both are able to give some premium features.
Considered AV receivers have the same number of channels 7.2. Regarding power, then TX-NR555 has such a W/Ohm ratio - 130/6 when AVR-S950H has a power of 90/8, 125/6. The THD is the same and is 0.08%.
Characteristics of digital to analog converter (DAC) are different, Hi-Grade 384 KHz/32-bit for TX-NR555 and AKM 192 KHz/32-bit for the AVR-S950H. 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 Onkyo TX-NR555 has support for AirPlay, and its competitor in our comparison - AirPlay, AirPlay 2. Spotify can be used on each receiver. The TX-NR555 can work with the audio stream from Deezer, TIDAL, Pandora, and the AVR-S950H can receive a content from Deezer, TIDAL, Pandora, Napster, SiriusXM, TuneIn Radio, iHeart Radio, Sound Cloud, Mood Mix. 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. The AVR-S950H can scale the input HDMI signal, unlike the TX-NR555. Dolby Vision technology found support only on the AVR-S950H.
The Onkyo TX-NR555 has 6/1 HDMI inputs/outputs versus 8/2 HDMI connectors of the Denon AVR-S950H. The HDMI Audio Return Channel (ARC) feature supports both devices. The HDMI eARC is available only on the AVR-S950H. The Consumer Electronics Control (CEC) feature is present in most modern AV receivers and the models in our comparison are no exception. The TX-NR555 supports the protection of digital content of the standard HDCP 2.2, versus HDCP 2.3 in the AVR-S950H. These compared receivers have a built-in phono stage for connecting a vinyl player.
Each of the AV receivers from our review supports 2 Multi-room zones. 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-S950H.
Both devices have support for Dolby Atmos multichannel audio format. The surround sound technology DTS:X is supported by devices under review.