I'm not really sure why it happens with my laptop but I get that too when I have my laptop plugged in. Most of the times it's a ground looping problem.

Take a look at this thread here

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Certain laptops, the ones with three pins going into the power brick rather than two, can suffer from ground loops when used with sound cards connected to amplified systems. I won't go into the technical jiggery-pokery of why this happens but trust me, it does (I've been suffering from it with my laptop!) One solution is to use a 2 pin power brick, or put tape over the earth pin on the plug, but that's a bit dodgy and can lead to potentially fatal electric shock! Another solution has been to use a Ground Loop Isolator, but these have traditionally been bulky and generall a bit crap (Beringher did one) However I've found a much better Isolator and thought I'd share it with you, I've ordered one and will let you know how it works when it arrives... it certainly looks like a better solution. http://www.xitel.com/product_gli.htm You can get these from here: http://www.discountdiscs.co.uk/Merc...gory_Code=Xitel Which seems to be the only UK based supplier I could find. Hope this helps.

Another note:

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... the hum is caused by RF interference you need one of these http://www.maplin.co.uk/module.aspx...=32799&doy=27m6

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You have a ground loop issue. Do a search for a ground loop isolator. Shouldn't be more that $20 -$30.

Hope this helps a bit.

plug in your laptop somewhere else ?

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thesuperglo - Flaming Popsicle [June 2007 Promo](full-on/dark/goa)

Been there done that... Most laptops have a crappy power supply that causes the problem. Anything connected to your laptop will suffer. Nomatter what the connection. You can pick up earth loop eliminators that will fix the problem for well under $50 USD.
If you lucky and its just an earth loop problem plugging things into different outlets and creating common grounds may fix your problem.

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i think you could try a ground loop isolator??? this works to get rid of the humm but i dont know if also for power supplies since shouldnt they have that built in??

I use a laptop in my setup and I spent many hours researching asking around and the problem is that most laptop power supplies have a crappy ac/dc converters.
You could always spend a few hundread on a 3rd party power supply and hope it works...

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