[Bug 35540] Using alsamixer/amixer after selecting a non-default sound card (System> Preferences> Sound> Default sound card) results in errors

[Daniel T. Chen]

Public bug reported:
https://launchpad.net/malone/bugs/35540

Affects: control-center (Ubuntu)
       Severity: Normal
       Priority: (none set)
         Status: Unconfirmed

Description:
debian/patches/23_default_soundcard_selector.patch needs to be modified
(one additional line) to set defaults.ctl.card in ~/.asoundrc.asoundconf
after the user selects a non-default sound card using the System>
Preferences> Sound> Default sound card menu. Otherwise, the following
error occurs when using alsamixer (or amixer) from the command line:

ALSA lib confmisc.c:1107:(snd_func_refer) Unable to find definition 'defaults.ctl.card'
ALSA lib conf.c:3493:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib confmisc.c:242:(snd_func_getenv) error evaluating default
ALSA lib conf.c:3493:(_snd_config_evaluate) function snd_func_getenv returned error: No such file or directory
ALSA lib conf.c:3962:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib control.c:817:(snd_ctl_open_noupdate) Invalid CTL default
amixer: Mixer attach default error: No such file or directory