An affordable AV receiver is always a good option to consider, so Onkyo TX-SR343 vs Marantz SR5011 comparison definitely makes sense.
A significant difference between the receivers in the number of channels, Onkyo TX-SR343 has 5.1 versus 7.2 for Marantz SR5011. Regarding power, then TX-SR343 has such a W/Ohm ratio - 100/6 when SR5011 has a power of 100/8, 140/6. The THD is the same and is 0.08%.
Characteristics of digital to analog converter (DAC) are different, TI Burr-Brown 192 KHz/24-bit for TX-SR343 and 192 KHz/24-bit for the SR5011. Only the SR5011 supports Bi-amping feature. The Marantz SR5011 can transmit an audio signal directly to the amplifier and bypasses any DSP processing. Rivals from our review have Bluetooth support. Only the SR5011 supports Spotify.
Only the Marantz SR5011 has support for High dynamic range (HDR). Compared AV receivers retain the quality of 4K/60Hz signal when transmitting from a source to a TV or projector. HDMI signal transmission in standby mode is implemented in each of the devices. The SR5011 can scale the input HDMI signal, unlike the TX-SR343. Dolby Vision technology found support only on the SR5011.
The Onkyo TX-SR343 has 4/1 HDMI inputs/outputs versus 8/2 HDMI connectors of the Marantz SR5011. The HDMI Audio Return Channel (ARC) feature supports both devices. Unfortunately, HDMI eARC is not available on monitored devices. 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. Receivers do not have a built-in phono stage for connecting a vinyl player. A voice control is not available. An ECO mode is only available for the SR5011. The setup assistant will help you configure Marantz SR5011.
Only the SR5011 has a Dolby Atmos multichannel audio format support. A surround technology DTS:X is supported only by the SR5011.