Disklavier

We recently purchased a new DGC1 playback Disklavier.  When we play
from a disk (piano only), the volume setting seems to loud.  I'd like
to be able to soften the sound.  The manual says that one can adjust
the volume using the LED volume indicators.  I have it set to -10.  

The manual also says to "Make sure the VOLUME knob on the Amplifier is
set to an appropriately audble level.  If the volume knob on the
Amplifier is tuned fully counterclockwise, no sound may be produced
even when you adjust the volume on the Control unit."

Adjusting this volume control on the Amplifier seems to have no
effect.  Is something wrong with my unit - or does this master volume
control on the Amplifier not have any effect on the volume of the
piano playback?

Thanks.

                         gary comfort