Volume control issue

Hi all,

I have read this issue in different ways, but every case is different and not all have an answer (none has worked for me).

I am running Mopidy service (although with normal mopidy happens the same) with Raspbian Jessie in my Pi 3.
I have the output through USB to a DAC+Amplif (not dangerous link) .I get a nice sound, but there is no way to control the volume, that seems to be to the maximum level.

I am using (or have tried) MPDdroid, Mopidy Mobile and Remotedely. And I have also installed Musicbox for controlling it from the laptop. No way to change volume or to mute it.

Any ideas?

Here is my config file (under /etc/mopidy):
(I have tried different values at “control = Master, PCM…”)

[core]
cache_dir = /var/cache/mopidy
config_dir = /etc/mopidy
data_dir = /var/lib/mopidy
#max_tracklist_length = 10000
restore_state = false

[logging]
config_file = /etc/mopidy/logging.conf
debug_file = /var/log/mopidy/mopidy-debug.log

[audio]
mixer = alsamixer
mixer_volume = 10
output = alsasink device=hw:1,0
#buffer_time =

[mpd]
enabled = true
hostname = ::
port = 6600
#password =
#max_connections = 20
#connection_timeout = 60
#zeroconf = Mopidy MPD server on $hostname
#command_blacklist =
#  listall
#  listallinfo
#default_playlist_scheme = m3u

[http]
enabled = true
hostname = ::
port = 6680
#static_dir =
#zeroconf = Mopidy HTTP server on $hostname

[stream]
#enabled = true
#protocols =
#  http
#  https
#  mms
#  rtmp
#  rtmps
#  rtsp
#metadata_blacklist =
timeout = 10000

[local]
enabled = true
#library = json
media_dir = /var/lib/mopidy/media
#scan_timeout = 1000
#scan_flush_threshold = 100
#scan_follow_symlinks = false
#excluded_file_extensions =
#  .directory
#  .html
#  .jpeg
#  .jpg
#  .log
#  .nfo
#  .png
#  .txt

[m3u]
playlists_dir = /var/lib/mopidy/playlists
#enabled = true
#base_dir = $XDG_MUSIC_DIR
#default_encoding = latin-1
#default_extension = .m3u8
#playlists_dir =

[softwaremixer]
enabled = true

[file]
#enabled = true
#media_dirs =
#  $XDG_MUSIC_DIR|Music
#  ~/|Home
#excluded_file_extensions =
#  .jpg
#  .jpeg
#show_dotfiles = false
#follow_symlinks = false
#metadata_timeout = 1000

[alsamixer]
card = 1
control = Master
min_volume = 30
max_volume = 70
volume_scale = cubic

[gmusic]
username = ******
password = ******
bitrate = 320
deviceid = ******


[somafm]
encoding = aac
quality = highest

[musicbox_webclient]
enabled = true
musicbox = false
websocket_host =
websocket_port =
on_track_click = ADD_ALL_BOTTOM