Hi pi-fi,
you can try to change the default volume for all alsa devices to 0dm.
/usr/share/alsa/init/default
#
# Default ALSA volume levels and setting when initialization database fails.
#
# Basic rules are:
# - keep volumes at minimal level, but sound should be hearable
# - enable standard outputs for playback and main microphone for recording
#
# **************************************************************************
# playback
# **************************************************************************
ENV{ppercent}:="75%"
ENV{cpercent}:="75%"
ENV{pvolume}:="-20dB"
ENV{cvolume}:="12dB"
ENV{has_pmaster_vol}:="false"
Change it so it looks like this:
#
# Default ALSA volume levels and setting when initialization database fails.
#
# Basic rules are:
# - keep volumes at minimal level, but sound should be hearable
# - enable standard outputs for playback and main microphone for recording
#
# **************************************************************************
# playback
# **************************************************************************
ENV{ppercent}:="75%"
ENV{cpercent}:="75%"
ENV{pvolume}:="0dB"
ENV{cvolume}:="12dB"
ENV{has_pmaster_vol}:="false"
Frank