It makes sense comparing Onkyo TX-SR343 vs Marantz SR7015 because they both are able to give some premium features.
A significant difference between the receivers in the number of channels, Onkyo TX-SR343 has 5.1 versus 9.2 for Marantz SR7015. Regarding power, then TX-SR343 has such a W/Ohm ratio - 100/6 when SR7015 has a power of 125/8, 165/6. The THD is 0.08% for the TX-SR343 but 0.05% for the SR7015. Only the SR7015 supports Bi-amping feature. The Marantz SR7015 can transmit an audio signal directly to the amplifier and bypasses any DSP processing. Rivals from our review have Bluetooth support. Only the SR7015 supports Spotify. HDMI signal transmission in standby mode is implemented in each of the devices. The SR7015 can scale the input HDMI signal, unlike the TX-SR343. Dolby Vision technology found support only on the SR7015.
The Onkyo TX-SR343 has 4/1 HDMI inputs/outputs versus 8/3 HDMI connectors of the Marantz SR7015. The HDMI Audio Return Channel (ARC) feature supports both devices. The HDMI eARC is available only on the SR7015. The Consumer Electronics Control (CEC) feature is present in most modern AV receivers and the models in our comparison are no exception. The TX-SR343 supports the protection of digital content of the standard HDCP 2.2, versus HDCP 2.3 in the SR7015. The SR7015 has a built-in phono stage for connecting a vinyl player. An ECO mode is only available for the SR7015. The setup assistant will help you configure Marantz SR7015.
Only the SR7015 has a Dolby Atmos multichannel audio format support. A surround technology DTS:X is supported only by the SR7015.