Voice in movies, mp3 and some games very low

Hello, I have a problem with very low voices in audio (games, movies, music)

The problem: Voice is very low in MP3, Some Games and most (streaming) video - often garbled with digital noise as well, but voice is always low. When playin music, it sounds like the singer is deep in a concrete stairwell, far from the rest of the band. In games, dialogue is unhearable and in many movies also.

I positively know that MP3 playback is affected and also Mpeg4 h264 video sound, but playback of other formats may be affected too.

Have a look / listen at this example - it doesn't matter the language is foreign to you, since you can't hear it anyway...:

http://youtu.be/nyVPbb-ZUow

(btw - I know the driver in the video is older, but that was one of the many failed fixes. Newest or older drives give the same result as in the video).

I have tried all the simple fixes suggested on this and a host of other fora.

- Adjusting Ac3 filter settings to stereo speakers
- Installing new codecs
- Removing all codecs
- Installing K-lite codec pack at trying to fix the issue with codec-tweaker
- Disabling sound devices
- Removing and reinstalling drivers, even trying older drivers
- Using different headphones, to see if they work
- Toggled Front audio connection detection
- Checked all properties and settings of the speakers and disabled and/or tweaked Enhancements
- I even fiddled with what codecs should handle what formats via codec-tweaker, but didnt strike gold

I am at a loss here, having spent 20+ hours searching and applying fixes and I need som advanced help. It is not a problem that can be fixed with toggling a simple setting in the sound/speaker properties.

It seem to be an issue that has become widespread since SP1, but I don't know for sure and I am not sure how long this problem has been affecting me, but it is more like a month or two, than the whole year since SP1 rolled out.

I have Windows 7 SP 1, Gigabyte x48 D6Q motherboard, Realtek HD Audio (onboard), external Logitech Sound Card (yes, I have tried disabling each to see if they mess eachother up) and headphones.

I hope someone can help!