Volume Control Command

[Andres]

Hello,
i build a Arcade cabinet, in which i am using a set of USB Arcade Buttons connected to the Raspberry via USB.
I'm using two red buttons for select and start which are working perfectly fine.
Now i would like to use two blue buttons to regulate the volume. I found an instruction on how to set this up in this post, which i followed. But Unfortunately it is not working after restarting the pi.
Triggerhappy works as far as i know, because after i failed setting up the Volume Buttons, i attempted to set up a command to shut the pi down with one of the volume buttons using this post, which worked.
That leads me in to guessing that the command, which i am using in the config is not working for me.
KEY_VOLUMEDOWN 1 /usr/bin/amixer sset PCM,0 2dB-
KEY_VOLUMEUP 1 /usr/bin/amixer sset PCM,0 2dB+
So the question is: Is there another command or way to get the two volume buttons working for a noob like me.

Pi Model or other hardware: Pi 3b
RetroPie Version Used: 4.2.9
Built From: Pre made SD Image on RetroPie website
USB Devices connected: Logitech k400
Controller used: They plug in via USB
Error messages received: n/a
Guide used: Guide i found and followed

Thank you

[Zigurana]

Are you sure Triggerhappy is running?
For me these keys were present, because my speaker-sets came with a usb-hid device where the two buttons represented as these two keys (vol up and down). Does your usb interface present itself as a keyboard as well? What buttons are the keys representing as? If you follow the links in my post in the other thread, you should find the commands to find this out.

[Andres]

I'm pretty shure Triggerhappy is running, because if it was not running it wouldn't have worked for the shut down hotkey.
I found the "name" of the buttons by using the "thd --dump /dev/input/event*" command in the post you recommendet and created a .cfg:

BTN_BASE3 1 /usr/bin/amixer sset PCM,0 2dB-
BTN_BASE4 1 /usr/bin/amixer sset PCM,0 2dB+

The buttons are connected via USB to the Raspberry and work great with the commands configured in emulationstation. The Speakers are plugged in to the 3,5mm klinke output of the pi.