Sound problem with power on

Hello,
I've got a serious problem of sound with my Umix-44 with DVS.
It seems to be linked to the power of the computer. When the computer is pluged to the electricity there is a continous bad digital noise. When the computer is running on the battery there is no more noise...
At home the noise is acceptable but when i'm moving to play in club the sound is very bad.
Do you have any idea to solve this problem ?
Thx
I've got a serious problem of sound with my Umix-44 with DVS.
It seems to be linked to the power of the computer. When the computer is pluged to the electricity there is a continous bad digital noise. When the computer is running on the battery there is no more noise...
At home the noise is acceptable but when i'm moving to play in club the sound is very bad.
Do you have any idea to solve this problem ?
Thx