It makes sense comparing Sony STR-ZA3100ES vs Onkyo TX-8020 because they both are able to give some premium features.
A significant difference between the receivers in the number of channels, Sony STR-ZA3100ES has 7.2 versus 2.0 for Onkyo TX-8020. Regarding power, then STR-ZA3100ES has such a W/Ohm ratio - 70/8, 90/6 when TX-8020 has a power of 90/6. The THD is 0.09% for the STR-ZA3100ES but 0.03% for the TX-8020. Only the STR-ZA3100ES supports Bi-amping feature. Each of the AV receivers can transmit an audio signal directly to the amplifier and bypasses any DSP processing.
Both models do not have WI-FI support. Only the STR-ZA3100ES has Bluetooth support. Competitors do not have built-in Spotify service.
Only the Sony STR-ZA3100ES has support for High dynamic range (HDR). Only the STR-ZA3100ES provides HDMI signal transmission in standby mode. Both competitors are not able to scale the HDMI signal. Dolby Vision technology found support only on the STR-ZA3100ES. Only the STR-ZA3100ES supports HDMI Audio Return Channel (ARC). The HDMI eARC is available only on the STR-ZA3100ES. Of the two receivers in our comparison, HDMI CEC is present in only the STR-ZA3100ES. The TX-8020 has a built-in phono stage for connecting a vinyl player. A voice control is not available. An ECO mode is not present in each of the AV receivers. The setup assistant will help you configure Sony STR-ZA3100ES.
Only the STR-ZA3100ES has a Dolby Atmos multichannel audio format support. A surround technology DTS:X is supported only by the STR-ZA3100ES.
The Sony STR-ZA3100ES is better receiver in this comparison. Check Sony STR-ZA3100ES price