Sound interference coming from laptop when using mains power

[long john]

When I am using my laptop to play music and it is on mains power there is an annoying humming or buzzing sound that is not there when on battery power. I need to have it on mains power when I am DJing - does anyyone know how to solve this?

Thank you!

[StewyGriffin]

Buy an external USB sound card. Sound cards that are built into laptops are no where near the quality of those in PC's due to space restrictions. If you have mains hum then the laptop will only exacerbate the problem.
A mains purifier may help also. Like this one http://www.russandrews.com/static/Mini_Purifie r.html

Stewy

[long john]

This is when using an external sound card. Hercules2. Ill look into the purifier. Thanks.

[LeMarchand]

Is the noise from the laptop itself, or the converter box on the mains cable?

[long john]

The noise is from the external speakers and increases when i increase the volume.

[SCOTS_FLLIC]

I get the buzzing noise when i stop playing tracks or I shut down realplayer, windows media player etc. The problem occurs when the laptop is running on both mains or battery power.

Can I just install the drivers again to fix this?