Good morning, gkkpch
Ok, mate, here we go again…new fresh install of 0.068 version. Pen was formatted.
Alsamixer untouched…choose SPDIF from “General Playback Option” and some radio web…no sound at all…
WHEN I COPY AND ENTER “amixer -c 0 set ‘IEC958’,16 unmute”
i get sound immediatly…

volumio@volumio:~$ amixer scontrols
Simple mixer control ‘Master’,0
Simple mixer control ‘Headphone’,0
Simple mixer control ‘Front’,0
Simple mixer control ‘Front Mic’,0
Simple mixer control ‘Front Mic Boost’,0
Simple mixer control ‘Surround’,0
Simple mixer control ‘Center’,0
Simple mixer control ‘LFE’,0
Simple mixer control ‘Line’,0
Simple mixer control ‘Line Boost’,0
Simple mixer control ‘IEC958’,0
Simple mixer control ‘IEC958 Default PCM’,0
Simple mixer control ‘IEC958’,1
Simple mixer control ‘IEC958’,2
Simple mixer control ‘IEC958’,3
Simple mixer control ‘IEC958’,16
Simple mixer control ‘Capture’,0
Simple mixer control ‘Capture’,1
Simple mixer control ‘Auto-Mute Mode’,0
Simple mixer control ‘Input Source’,0
Simple mixer control ‘Input Source’,1
Simple mixer control ‘Loopback Mixing’,0
Simple mixer control ‘Rear Mic’,0
Simple mixer control ‘Rear Mic Boost’,0
volumio@volumio:~$ amixer -c 0 get ‘IEC958’
Simple mixer control ‘IEC958’,0
Capabilities: pswitch pswitch-joined
Playback channels: Mono
Mono: Playback [on]
volumio@volumio:~$ amixer -c 0 get ‘IEC958’,16
Simple mixer control ‘IEC958’,16
Capabilities: pswitch pswitch-joined
Playback channels: Mono
Mono: Playback [off]
amixer -c 0 set ‘IEC958’,16 unmute
Simple mixer control ‘IEC958’,16
Capabilities: pswitch pswitch-joined
Playback channels: Mono
Mono: Playback [on]
I GET SOUND WITH THIS COMMAND

volumio@volumio:~$ amixer -c 0 set ‘IEC958’ unmute
Simple mixer control ‘IEC958’,0
Capabilities: pswitch pswitch-joined
Playback channels: Mono
Mono: Playback [on]
Hope this can help you, mate
Cheers