Comment 6 for bug 1440675

I agree with Daniel that this would be helpful. While it is unlikely that alsamixer is not installed on GNU/Linux, it is also unlikely that a GUI for the ALSA mixer is installed and available in the desktop environment's application menu. If users look around for that, they'll probably just find pavucontrol or DE-specific programs for controlling PulseAudio and get confused. In Crossfade 0.90, I put icons for both pavucontrol and xfce4-mixer on the desktop. I think this is helpful albeit confusing and put a sentence about it in the manual, but it would be great if I could remove the xfce4-mixer icon, especially since that application is discontinued with Xfce 4.12, and have Mixxx launch alsamixer.

The button should open the controls for the sound card set as the master output (or whatever sound card JACK is using) by default. This can be done with the -c command line option for alsamixer. Otherwise, alsamixer will probably show controls for the onboard sound card and users may get confused looking for how to switch to their DJ sound card (although ALSA mixer makes it clear how to do this if one takes a few seconds to try looking around).

If Audacity and VLC, which are also cross-platform, provide similar controls, it could be helpful to see what they do on Windows and OS X.