The Marantz NR1609 vs Denon AVR-S660H comparison proves that these receivers have many common features.
A significant difference between the receivers in the number of channels, Marantz NR1609 has 7.2 versus 5.2 for Denon AVR-S660H. Regarding power, then NR1609 has such a W/Ohm ratio - 50/8, 70/6 when AVR-S660H has a power of 75/8, 100/6. The THD is the same and is 0.08%.
Characteristics of digital to analog converter (DAC) are different, 192 KHz/24-bit for NR1609 and 192 KHz/32-bit for the AVR-S660H. Only the NR1609 supports Bi-amping feature. The Marantz NR1609 can transmit an audio signal directly to the amplifier and bypasses any DSP processing.
WI-FI modules have the same characteristics: 2.4/5GHz. Rivals from our review have Bluetooth support. The Apple Music service is implemented on considered devices: AirPlay, AirPlay 2. Spotify can be used on each receiver. The NR1609 can work with the audio stream from Deezer, Pandora, TuneIn Radio, and the AVR-S660H can receive a content from Deezer, TIDAL, Pandora, SiriusXM, Napster, SoundCloud. HDMI signal transmission in standby mode is implemented in each of the devices. Both rivals can scale the resolution of the incoming HDMI signal. The HDR standard - Dolby Vision is supported by these receivers.
The Marantz NR1609 has 8/1 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 NR1609 supports the protection of digital content of the standard HDCP 2.2, versus HDCP 2.3 in the AVR-S660H. These compared receivers have a built-in phono stage for connecting a vinyl player. Supported voice control technologies are identical - Amazon Alexa, Google Assistant, Siri, Josh.AI. It is also worth noting that the ECO mode is presented in each of the receivers. Both NR1609 and AVR-S660H can be configured using the Setup assistant.
Only the NR1609 has a Dolby Atmos multichannel audio format support. A surround technology DTS:X is supported only by the NR1609.