Mixer controls on the HiFiBerry boards

The HiFiBerry DAC+ and Amp/Amp+ comes with integrated volume control.


In some distributions, the needed tools are not installed by default. Therefore you should install them first. On Debian based distributions this can be done with the following command:

sudo apt-get install alsa-utils

Change volume

The easiest way is using “alsamixer”. You can also use “amixer” if you want to set a specific volume non-interactively.

Controls of the cards


While there are a lot of mixer controls at the DAC+, you only need to care about one named “PCM”.

amixer sset PCM 90%

All other mixer control allow access to low-level functions of the sound chip. You won’t need them. Unfortunately it is not easy to remove these controls as they are part of a kernel driver that is not maintained by us. Just make sure, the “Playback Boost” is set to 0%.
To get the full output volume without clipping, the settings should be like this:

amixer sset 'PCM' 96%
amixer sset 'Playback Boost' 0%


There are 2 controls: Master and Channels. With the master control you control the overall volume while “Channels” can be used to set different volumes on the left and right channel. Note that excessive volumes can damage your speakers. Therefore we recommend setting the volume not too high on startup.

amixer sset Master 70%
amixer sset Channels 70%,70%

Store/restore volume settings

On Raspbian shutdown a shutdown script is used to store the current volume settings. However many people shutdown their system by removing the power (not optimal, but usually this works without problems). In this case, the latest volume settings are not stored. You can do this by hand with the command

alsactl store
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  • Avatar
    Bruno Beaufils

    'PCM' is not present in DAC+ Standard on my Raspberry Pi 2, using Debian jessie. One should use 'Digital' instead.

    Edited by Bruno Beaufils
  • Avatar
    J D

    I can confirm that this KB is not relevant with the DAC+ Pro. It should be:

    $ amixer sset 'Analogue Playback Boost' 0%
    $ amixer sset 'Digital' 100%

    100% seems to be 0 db and not 96%:
    Front Left: Playback 207 [100%] [0.00dB] [on]
    Front Right: Playback 207 [100%] [0.00dB] [on]

    Might be worth to update the KB :)

  • Avatar
    Robin Miller

    I'm wondering if this article is written confusingly or if I am the one with a misunderstanding... To get "the full output volume without clipping", the only thing is not to have any Playback Boost, right? The other setting 'PCM' or 'Digital' is not relevant, but the article makes it sound like you need to have that set to 96% to avoid clipping...