Yamaha YAS-108 Owner's Manual page 45

The volume decreases when the unit is
turned on
To prevent excessive loudness, the unit automatically controls
its volume within a certain level when the unit is turned on. Turn
up the volume as required. For details, see the following:
– "Basic procedure for playback" (p.27)
No surround effect
Select surround playback or 3D surround playback. For details,
see the following:
– "Playback with 3D surround sound" (p.29)
– "Playback with surround sound" (p.29)
Turn up the volume. For details, see the following:
– "Basic procedure for playback" (p.27)
Change the digital audio output setting on the TV or playback
device to Bitstream.
Set the TV volume to minimum. For details, see the following:
– "Basic procedure for playback" (p.27)
The listening position should be at some distance from the unit.
Noise is heard
Move those devices away from the unit.
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