Sound is zero when start playing

I got my pc connected via s/pdif to my receiver. However, when I start playing music the sound mutes. I have to put the sound up in Ubuntu itself to hear the music playing.

The output of alsamixer shows two s/pdif outputs, but it isn’t playing via the default
PCM.

My config file:

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

[logging]
color = true
console_format = %(levelname)-8s %(message)s
debug_format = %(levelname)-8s %(asctime)s [%(process)d:%(threadName)s] %(name)s\n %(message)s
config_file = /etc/mopidy/logging.conf
debug_file = /var/log/mopidy/mopidy-debug.log

[local]
media_dir = /home/joeri/Music

[m3u]
playlists_dir = /var/lib/mopidy/playlists

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

[audio]
output = alsasink device=hw:0,1

And the output of aplay:

**** List of PLAYBACK Hardware Devices ****
card 0: Generic [HD-Audio Generic], device 0: ALC887-VD Analog [ALC887-VD Analog]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 0: Generic [HD-Audio Generic], device 1: ALC887-VD Digital [ALC887-VD Digital]
Subdevices: 0/1
Subdevice #0: subdevice #0
card 1: NVidia [HDA NVidia], device 3: HDMI 0 [HDMI 0]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 1: NVidia [HDA NVidia], device 7: HDMI 1 [HDMI 1]
Subdevices: 1/1
Subdevice #0: subdevice #0

Nobody has an idea ?