An affordable AV receiver is always a good option to consider, so Onkyo TX-NR545 vs Denon AVR-X4000 comparison definitely makes sense.
Considered AV receivers have the same number of channels 7.2. Regarding power, then TX-NR545 has such a W/Ohm ratio - 100/6 when AVR-X4000 has a power of 125/8, 165/6. The THD is 0.08% for the TX-NR545 but 0.05% for the AVR-X4000.
Characteristics of digital to analog converter (DAC) are different, Hi-Grade 384 KHz/32-bit for TX-NR545 and 192 KHz/24-bit for the AVR-X4000. Both the TX-NR545 and the AVR-X4000 support Bi-amping. 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 Apple Music service is implemented on considered devices: AirPlay. Spotify can be used on each receiver. The TX-NR545 can work with the audio stream from Tunein Radio, and the AVR-X4000 can receive a content from Pandora, Sirius XM.
Only the Onkyo TX-NR545 has support for High dynamic range (HDR). 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-X4000 can scale the input HDMI signal, unlike the TX-NR545. The HDR standard - Dolby Vision is not supported by these receivers.
The Onkyo TX-NR545 has 6/1 HDMI inputs/outputs versus 7/3 HDMI connectors of the Denon AVR-X4000. The HDMI Audio Return Channel (ARC) feature supports both devices. Unfortunately, HDMI eARC is not available on monitored devices. The Consumer Electronics Control (CEC) feature is present in most modern AV receivers and the models in our comparison are no exception. Both models support the standard HDCP 2.2. The AVR-X4000 has a built-in phono stage for connecting a vinyl player.
The TX-NR545 supports 2 Multi-room zones, versus 3 for the AVR-X4000. A voice control is not available. An ECO mode is not present in each of the AV receivers. Both TX-NR545 and AVR-X4000 can be configured using the Setup assistant.
Only the TX-NR545 has a Dolby Atmos multichannel audio format support. The receivers do not support the surround sound technology DTS:X.