@ThegoLopez What Desktop do you use, have you installed pavucontrol?
Are you talking about controlling the volume or about a sound equalizer?
If volume, have you tried switching off every sound device, which is not used in your Desktops sound configuration?
I have only one input and one output device enabled, as you can see in the screenshot.
pacman -Qi virtualbox
Name : virtualbox
Version : 5.0.18-1
Still have to use iomem=relaxed to boot Live CD, then again on the first boot.
Install linux-headers, because without dkms will not work:
sudo pacman -S linux-headers
dkms will start to build virtualbox modules, then reboot without iomem=relaxed
I made this video, but it is in German: