per vedere i permessi del mixer:
$ ls -l /dev/mixer*
dovrebbe ritornarti qualcosa del genere
lrwxrwxrwx 1 root audio 11 2004-03-21 11:09 /dev/mixer ->
/dev/mixer0
crw-rw-rw- 1 root audio 14, 0 2004-03-21 11:09 /dev/mixer0
crw-rw-rw- 1 root audio 14, 16 2004-03-21 11:09 /dev/mixer1
crw-rw-rw- 1 root audio 14, 32 2004-03-21 11:09 /dev/mixer2
crw-rw-rw- 1 root audio 14, 48 2004-03-21 11:09 /dev/mixer3
nota i permessi associati ... per cambiarli:
$ man chmod
per usare alsamixer
$ man alsamixer
$ alsamixer