How can I play simulteanously two different audio using headphones for one and internal speakers for the other?

Question

How can I play audio through both speakers and headphones in Ubuntu 14 LTS? I want to use mixxx to play deck 1 through speakers and deck 2 in headphones. TIA

Answer 1

• The easiest way is to use a usb headphone (or a 5$ usb audio device to plug your headphone) , and to select this usb sound device for deck2 in Mixxx sound preferences .

• Another way depends on your soundcard:
  There is a possibility to create a new audio device just by activating "independent HP" in Alsamixer .

  First, run "alsamixer " in a maximized terminal , and search if you have a fader called "independant" (the name is under the fader, see screen capture at the end)
  (sometimes , if you see only one fader, you have to press F6 function key and select your main soundcard if it is not the default )
  If no "independant" fader, no chance .
  Else, follow the following steps after disconnecting you headphone jack and closing all audio software (close also the previous alsamixer pressing "esc" in its terminal) :

  • Stop pulseaudio copying and running successively these 3 commands in a terminal :
    mkdir ~/.pulse
echo autospawn=no > ~/.pulse/client.conf
pulseaudio -k

  • Relaunch alsamixer in a terminal, use left/right arrows keys to move to the "independant" fader, change its state to "enabled" using up arrow key.
    Also verify "speaker" and "headphones" fader are not muted ("MM" under the fader means "muted", "00" is ok.)
    Now, as in "independent" mode, a new audio output is created for headphone only (called "hw:0,2"), in addition to the default device (hw:0,0) which is for speaker.

  • Go to the Mixxx sound preferences and select "soundcard_name (hw:0,0)" for deck1, "soundcard_name (hw:2,0)" for deck2, "none" for main and headphones.

  • Later, you can revert to pulseaudio running echo autospawn=yes > ~/.pulse/client.conf then pulseaudio -D

(the "independent HP " tips creating new headphone device is from here )