Denon AVR-S640H vs Onkyo TX-SR494 – that is a question.
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-SR494 has a power of 135/6. 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-SR494 is equipped with AKM 384 KHz/32-bit. The Bi-amping function is implemented only in the Onkyo TX-SR494. Both Denon AVR-S640H and Onkyo TX-SR494 can transmit an audio signal directly to the amplifier and bypasses any DSP processing.
Wireless Internet connection via WIFI is only possible with AVR-S640H. Each of the receivers has a Bluetooth connector. The AVR-S640H has access to the Spotify service. 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-SR494. None of the devices can increase the resolution of the incoming video signal. Operation with the Dolby Vision is only possible with the AVR-S640H.
The number of HDMI inputs/outputs varies depending on the receiver, the AVR-S640H has 5/1, and the TX-SR494 has 4/1. HDMI Audio Return Channel is implemented in both devices. HDMI eARC is not supported by the AVR-S640H and the TX-SR494. When comparing receivers, it becomes clear that each of the rivals can work with HDMI CEC. AVR-S640H and TX-SR494 support the standard HDCP 2.2. In the presence of a built-in phono stage for connecting a vinyl player only at Denon AVR-S640H. There is an ECO mode in AVR-S640H. The Denon AVR-S640H and the Onkyo TX-SR494 can be properly configured using the setup assistant.
A Dolby Atmos multichannel audio format is available only in the TX-SR494. Only in the TX-SR494 realized a DTS:X surround technology.