Onkyo TX-SR353 vs Onkyo TX-RZ840 comparison definitely makes sense.
A significant difference between the receivers in the number of channels, Onkyo TX-SR353 has 5.1 versus 9.2 for Onkyo TX-RZ840. Regarding power, then TX-SR353 has such a W/Ohm ratio - 140/6 when TX-RZ840 has a power of 180/6. The THD is the same and is 0.08%.
Characteristics of digital to analog converter (DAC) are different, 192 KHz/24-bit for TX-SR353 and AKM 384 KHz/32-bit for the TX-RZ840. Only the TX-RZ840 supports Bi-amping feature. The Onkyo TX-RZ840 can transmit an audio signal directly to the amplifier and bypasses any DSP processing.
Only the Onkyo TX-RZ840 can connect to the Internet via WI-FI. Rivals from our review have Bluetooth support. Only the TX-RZ840 supports Spotify. HDMI signal transmission in standby mode is implemented in each of the devices. Both competitors are not able to scale the HDMI signal. Dolby Vision technology found support only on the TX-RZ840.
The Onkyo TX-SR353 has 4/1 HDMI inputs/outputs versus 7/2 HDMI connectors of the Onkyo TX-RZ840. The HDMI Audio Return Channel (ARC) feature supports both devices. The HDMI eARC is available only on the TX-RZ840. 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 TX-RZ840 has a built-in phono stage for connecting a vinyl player. An ECO mode is not present in each of the AV receivers. The setup assistant will help you configure Onkyo TX-RZ840.
Only the TX-RZ840 has a Dolby Atmos multichannel audio format support. A surround technology DTS:X is supported only by the TX-RZ840.