It’s strongly recommended to compare different receivers if you want to choose the best one: Denon AVR-S640H vs Onkyo TX-NR676.
The number of channels for receivers is different - 5.2 versus 7.2, respectively, for devices. In terms of power, there are differences, the AVR-S640H has such a ratio W/Ohm - 75/8, 100/6, while the TX-NR676 has a power of 165/6. A common feature for devices is the same total harmonic distortion - 0.08%.
The manufacturer installed different DACs, the AVR-S640H received the model 192 KHz/32-bit, but the TX-NR676 is equipped with AK4458 384 KHz/32-bit. The Bi-amping function is implemented only in the Onkyo TX-NR676. Both Denon AVR-S640H and Onkyo TX-NR676 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, AirPlay 2 versus AirPlay respectively. Access to the Spotify service is on each of the competitors. The number of available streaming services varies for receivers, the Denon AVR-S640H works with Deezer, TIDAL, Pandora, Napster, SiriusXM, TuneIn Radio, iHeart Radio, Sound Cloud, but the Onkyo TX-NR676 works with Deezer, TIDAL, Pandora, TuneIn Radio. 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 AVR-S640H and the TX-NR676. None of the devices can increase the resolution of the incoming video signal. Each of the participants of the comparison has a Dolby Vision.
The number of HDMI inputs/outputs varies depending on the receiver, the AVR-S640H has 5/1, and the TX-NR676 has 7/2. HDMI Audio Return Channel is implemented in both devices. HDMI eARC is not supported by the AVR-S640H and the TX-NR676. When comparing receivers, it becomes clear that each of the rivals can work with HDMI CEC. AVR-S640H and TX-NR676 support the standard HDCP 2.2. Like most receivers, our models have a built-in phono stage for connecting a vinyl player. There is an ECO mode in either AV receiver. The Denon AVR-S640H and the Onkyo TX-NR676 can be properly configured using the setup assistant.
A Dolby Atmos multichannel audio format is available only in the TX-NR676. Only in the TX-NR676 realized a DTS:X surround technology.