tuedel@tuedel-o-mat:~$ speaker-test -c2 -Dch51dup -twav
speaker-test 1.0.13
Playback device is ch51dup
Stream parameters are 48000Hz, S16_LE, 2 channels
WAV file(s)
ALSA lib pcm_dmix.c:864:(snd_pcm_dmix_open) unable to open slave
Playback open error: -16,Device or resource busy
ALSA lib pcm_dmix.c:864:(snd_pcm_dmix_open) unable to open slave
Playback open error: -16,Device or resource busy
ALSA lib pcm_dmix.c:864:(snd_pcm_dmix_open) unable to open slave
Playback open error: -16,Device or resource busy
ALSA lib pcm_dmix.c:864:(snd_pcm_dmix_open) unable to open slave
Playback open error: -16,Device or resource busy
ALSA lib pcm_dmix.c:864:(snd_pcm_dmix_open) unable to open slave
Playback open error: -16,Device or resource busy
ALSA lib pcm_dmix.c:864:(snd_pcm_dmix_open) unable to open slave
Playback open error: -16,Device or resource busy