Having had an opportunity to test Sony STR-DH590 vs Pioneer Elite SC-LX904, I’d like to share my impression here to facilitate your choice of a new AV receiver.
The number of channels for receivers is different - 5.2 versus 11.2, respectively, for devices. In terms of power, there are differences, the STR-DH590 has such a ratio W/Ohm - 145/6, while the Elite SC-LX904 has a power of 140/8. The value of total harmonic distortion is also different, and for the STR-DH590 it is 0.09%, but for the Elite SC-LX904 it is 0.08%.
The manufacturer installed different DACs, the STR-DH590 received the model 192 KHz/32-bit, but the Elite SC-LX904 is equipped with ES9026PRO 384 KHz/32-bit. The Bi-amping function is implemented only in the Pioneer Elite SC-LX904. Both Sony STR-DH590 and Pioneer Elite SC-LX904 can transmit an audio signal directly to the amplifier and bypasses any DSP processing. Each of the receivers has a Bluetooth connector. The Elite SC-LX904 has access to the Spotify service.
The HDR10 function is present in each of the rivals. 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 STR-DH590 and the Elite SC-LX904. Video scaling is only possible with the Elite SC-LX904. Each of the participants of the comparison has a Dolby Vision.
The number of HDMI inputs/outputs varies depending on the receiver, the STR-DH590 has 4/1, and the Elite SC-LX904 has 7/3. HDMI Audio Return Channel is implemented in both devices. HDMI eARC is only supported by the Elite SC-LX904. When comparing receivers, it becomes clear that each of the rivals can work with HDMI CEC. The STR-DH590 has support for the standard HDCP 2.2, compared to the Elite SC-LX904, which supports the standard HDCP 2.3. In the presence of a built-in phono stage for connecting a vinyl player only at Pioneer Elite SC-LX904. There is an ECO mode in neither AV receiver. The Pioneer Elite SC-LX904 can be properly configured using the setup assistant.
A Dolby Atmos multichannel audio format is available only in the Elite SC-LX904. Only in the Elite SC-LX904 realized a DTS:X surround technology.