The following is what I did to set up Beats Audio on the HP Envy dv7t-7200 (Jan 2013). This model has 3 speakers total.
You need installed:
1) Create or edit /etc/modprobe.d/acpi-base.conf , and insert the following line:
options snd-hda-intel model=ref
2) As root, create the following files:
3) Open /etc/acpi/events/headphone for editing, and edit such that the entirety of the file is this:
*That's it, just those two lines. No bash header or anything. Save the file.
4) Open /etc/acpi/headphone.sh for editing, and paste the following:
case $3 in
"plug" ) amixer set Front mute;;
"unplug") amixer set Front unmute;;
5) Make the script executable:
sudo chmod u+x /etc/acpi/headphone.sh
6) Enable the acpi daemon at startup in whatever way is appropriate for you; put 'acpid' in a startup script somewhere, start it yourself at boot every time by executing acpid . In my case, Arch Linux
# systemctl enable acpid
7) Reboot. Rock out.
*) The filename for the alsa-base.conf may be different. Use what is present and working.
*) In step 4, you may need to change 'Front' to whatever alsamixer has designated to your speakers. If there are multiple commands which should be issued, best bet is to include them separately:
"plug" ) amixer set Master mute; amixer set Front mute;;
The intent is that the steps concerning the acpi handler and script be conflated with whatever steps the user (such as W. Goeman) took to enable their sound so that headphone detection is simulated. Hopefully this helps the OP.
I apologize for the necromancy, but this model is becoming increasingly common and the solutions available are poor, incomplete, and rare.