Further investigations, speaker-test throws this errors:
> Unable to set hw params for playback: Cannot allocate memory
> Setting of hwparams failed: Cannot allocate memory
output of "aplay -l":
**** List of PLAYBACK Hardware Devices ****
card 0: HDMI [HDA Intel HDMI], device 3: HDMI 0 [HDMI 0]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 0: HDMI [HDA Intel HDMI], device 7: HDMI 1 [HDMI 1]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 0: HDMI [HDA Intel HDMI], device 8: HDMI 2 [HDMI 2]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 0: HDMI [HDA Intel HDMI], device 9: HDMI 3 [HDMI 3]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 0: HDMI [HDA Intel HDMI], device 10: HDMI 4 [HDMI 4]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 1: PCH [HDA Intel PCH], device 0: ALC269VC Analog [ALC269VC Analog]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 1: PCH [HDA Intel PCH], device 1: ALC269VC Digital [ALC269VC Digital]
Subdevices: 1/1
Subdevice #0: subdevice #0
Output of "speaker-test -D hw:HDMI,3 -c 2 -r 48000":
speaker-test 1.2.2
Playback device is hw:HDMI,3
Stream parameters are 48000Hz, S16_LE, 2 channels
Using 16 octaves of pink noise
Rate set to 48000Hz (requested 48000Hz)
Buffer size range from 64 to 8544000
Period size range from 32 to 4272000
Using max buffer size 8544000
Periods = 4
Unable to set hw params for playback: Cannot allocate memory
Setting of hwparams failed: Cannot allocate memory