Hey guys, hopefully someone can shed some light on this as I'm really confused.

My setup: shure Mic > alesis multimix 4 usb mixer > laptop (usb obv) > ableton live.

Now this setup worked perfectly through my old comp but since I've tried to set it up with my new laptop everytime the mixer is on I get an awfull hissing sound. This is even when the gain and levels and everything are off on the mixer.. It's just always there. When the level is set right on the mixer so there should be no clipping atall, it clips like hell.. No matter what you do. All my settings are how they should be in ableton and on the mixer like I always have them but I just can't get rid of the hissing and clipping! I've tried different mic's and all but then realised even when you have the mixer on with nothing plugged in theres still the hiss. ARGH!

I'm thinking maybe its something to do with the soundcard? The mixer it self works fine with other computers its only when I plug into my laptop it seems.. Can't think of anything else.

Any ideas?
You've got some sort of ground loop hiss going on there. Try out different outputs and see if anything happens after plugging/unplugging laptop power cord. Also, if you are using a surge protector, make sure you don't have any other electronics that may cause interference connected to it as well (fridge / microwave). You may also want to use separate outlets for the laptop and the mixer.
Thanks, tried everything you said but nothing made a difference. Still the hiss remains and still even though the level is in the green, just below 0dB on the mixer when ever I play anything I just get mass clipage coming through. Tried all 4 channels aswell and still the same problem.

Any other ideas?