It's a MSI laptop with an AMD CPU. Might be the AMD is the issue since I have read that laptops with AMD often have problems with sound and that fits with my laptop too. On all distributions what I have tried so far, the volume of the speakers is pretty low. Where GNOME are always a bit better than KDE. I might get myself a new laptop soon anyway. One with an Intel CPU. That might help.
Laptop: DELL E6500 with LED backlight
CPU: Intel Core 2 Duo P8700
RAM: 4096MB (2048x2) DDR2 800
NVIDIA Quatro NVS160M 256 MB / 320 GB HDD/