Sony STR-DH590 Help Manual page 23

Sound
Button
field
Headphone(2ch)
*
You can also use FRONT SURROUND on the remote control.
Related Topic
Selecting a sound field
Display
panel
There is no button to select [Headphone(2ch)]. This mode is selected
automatically if you use headphones (Other sound fields cannot be selected).
HP 2CH Plays back 2-channel audio signals without adding any surround effect.
Sound from monaural and multi-channel audio signals are output after being
converted into a 2-channel signal.
4-731-210-11(1) Copyright 2018 Sony Corporation
Effects of the sound field
23