softvol boost increase alsa volume

One thing I liked with pulseaudio was increasing the volume to more than 100%. Although audiophiles may disagree, I need to increase the volume beyond 100% so I could hear some movies with low sound particularly voice dialogues.

I missed that feature in alsa. It turns out that this is built-in. Not many know about this, and those who do have issues configuring alsa softvol.

After trawling through much www research, this is what works for me. All one needs is a properly configured ~/.asoundrc file.

$ cat ~/.asoundrc
defaults.pcm.!card 0
defaults.pcm.!device 0
defaults.pcm.!ctl 0

pcm.!default {
    type asym
    playback.pcm "plug:softvol"
    capture.pcm "plug:dsnoop"
}
pcm.softvol {
    type softvol
    slave.pcm "dmix"
    control { name "PCM"; card 0; }
    #max_dB 32.0
    max_dB 20.0
    min_dB -5.0
}

Note that this uses PCM as your volume slider. So config your volume hotkeys (or triggers) to manipulate PCM, rather than Master. Set your Master level to 100% or whatever max suitable, and increase/decrease PCM for audio volume.