The Onkyo TX-SR383 vs Denon AVR-S660H comparison proves that these receivers have many common features.
A significant difference between the receivers in the number of channels, Onkyo TX-SR383 has 7.2 versus 5.2 for Denon AVR-S660H. Regarding power, then TX-SR383 has such a W/Ohm ratio - 100/8, 135/6 when AVR-S660H has a power of 75/8, 100/6. The THD is 0.09% for the TX-SR383 but 0.08% for the AVR-S660H.
Characteristics of digital to analog converter (DAC) are different, 192 KHz/24-bit for TX-SR383 and 192 KHz/32-bit for the AVR-S660H. None of the models support Bi-amping. Sound transmission directly to the amplifier in Pure direct (straight) mode is not implemented in these models. Rivals from our review have Bluetooth support. Only the AVR-S660H supports Spotify. HDMI signal transmission in standby mode is implemented in each of the devices. The AVR-S660H can scale the input HDMI signal, unlike the TX-SR383. Dolby Vision technology found support only on the AVR-S660H.
The Onkyo TX-SR383 has 4/1 HDMI inputs/outputs versus 6/1 HDMI connectors of the Denon AVR-S660H. The HDMI Audio Return Channel (ARC) feature supports both devices. The HDMI eARC is available only on the AVR-S660H. The Consumer Electronics Control (CEC) feature is present in most modern AV receivers and the models in our comparison are no exception. The TX-SR383 supports the protection of digital content of the standard HDCP 2.2, versus HDCP 2.3 in the AVR-S660H. The AVR-S660H has a built-in phono stage for connecting a vinyl player. An ECO mode is only available for the AVR-S660H. The setup assistant will help you configure Denon AVR-S660H.
Only the AVR-S660H has a Dolby Atmos multichannel audio format support. A surround technology DTS:X is supported only by the AVR-S660H.