It’s strongly recommended to compare different receivers if you want to choose the best one: Onkyo TX-RZ820 vs Pioneer VSX-531.
The number of channels for receivers is different - 7.2 versus 5.1, respectively, for devices. In terms of power, there are differences, the TX-RZ820 has such a ratio W/Ohm - 160/8, while the VSX-531 has a power of 80/8, 140/6. A common feature for devices is the same total harmonic distortion - 0.08%.
The manufacturer installed different DACs, the TX-RZ820 received the model AK4458 384 KHz/32-bit, but the VSX-531 is equipped with 192 KHz/24-bit. The Bi-amping function is implemented only in the Onkyo TX-RZ820. Both Onkyo TX-RZ820 and Pioneer VSX-531 can transmit an audio signal directly to the amplifier and bypasses any DSP processing. Each of the receivers has a Bluetooth connector. The TX-RZ820 has access to the Spotify service. The quality of 4K/60Hz signal remains unchanged when transmitting from a source to a TV or projector via HDMI for both receivers. Signaling over HDMI in standby mode can provide the TX-RZ820 and the VSX-531. None of the devices can increase the resolution of the incoming video signal. Operation with the Dolby Vision is only possible with the TX-RZ820.
The number of HDMI inputs/outputs varies depending on the receiver, the TX-RZ820 has 7/2, and the VSX-531 has 4/1. HDMI Audio Return Channel is implemented in both devices. HDMI eARC is not supported by the TX-RZ820 and the VSX-531. When comparing receivers, it becomes clear that each of the rivals can work with HDMI CEC. TX-RZ820 and VSX-531 support the standard HDCP 2.2. In the presence of a built-in phono stage for connecting a vinyl player only at Onkyo TX-RZ820. Voice control of the basic functions of the receiver is not realized in both models. There is an ECO mode in either AV receiver. The Onkyo TX-RZ820 can be properly configured using the setup assistant.
A Dolby Atmos multichannel audio format is available only in the TX-RZ820. Only in the TX-RZ820 realized a DTS:X surround technology.