The sound is distorted

The volume of the unit is too high.
Turn down the volume. If “ECO Mode” in the “Setup” menu is set to “On”, set it to “Off”. For details, see the following:

“Setting the use of the eco mode”

A device (such as an external power amplifier) connected to the unit’s audio output jacks is not turned on.
Turn on all devices connected to the unit’s audio output jacks.

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