An affordable AV receiver is always a good option to consider, so Sony STR-DH590 vs Sony STR DH550 comparison definitely makes sense.
Considered AV receivers have the same number of channels 5.2. Regarding power, then STR-DH590 has such a W/Ohm ratio - 145/6 when STR DH550 has a power of 90/6. The THD is the same and is 0.09%.
Characteristics of digital to analog converter (DAC) are different, 192 KHz/32-bit for STR-DH590 and 192 KHz/24-bit for the STR DH550. None of the models support Bi-amping. The Sony STR-DH590 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-DH590 has Bluetooth support. Each of these units does not support Apple Music. Competitors do not have built-in Spotify service. Only the STR-DH590 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-DH590.
Each receiver has 4/1 HDMI inputs/outputs. 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 not present in each of the AV receivers. Unfortunately, the setup assistant is not available in each of the models.
None of the rivals equipped with Dolby Atmos multichannel audio decoder. The receivers do not support the surround sound technology DTS:X.