Adjusting the volume of each channel to match the input source (Channel Level Adjust)
The volume of each channel can be changed while listening to music. You can set this for each input source.
Press OPTION.
The option menu screen is displayed.
Use 
to select “Channel Level Adjust”, then press ENTER.
to select “Channel Level Adjust”, then press ENTER.The channel level adjust screen is displayed.
Use to select the channel that you wish to adjust.
to select the channel that you wish to adjust.Use 
to adjust the volume.
to adjust the volume.|
–12.0 dB – +12.0 dB (Default : 0.0 dB) |
Select “Reset” and press ENTER if you want to restore the adjustment values of the various channels to “0.0 dB” (default).
Headphone volume can be adjusted when a headphone is connected.
“Channel Level Adjust” settings are stored for each input source.
You can only set this for speakers that output audio. In addition, you cannot set this when in the menu “HDMI Audio Out” is set to “TV”. link