So first off, I have a Dell Inspiron 15 3542. I got this second hand from an acquaintance for basically nothing without the HDD. I use a UCA202 USB running to a UB1202 mixer , and acts the same way with my Xenyx 302USB mixer (haven't tested mic interference, nor care to; what matters is it has the same sound) with different cables. So when I plug in the power, even without a battery in the laptop, there is a loud crackling interference that changes when both the mouse or touchpad moves the cursor around and such (the mouse is not causing any issues, so it's out of the question). When running direct output to my headphones (HD439) and monitors (HR824), I can hear it more when I turn it louder. Now, when I run it to a Lexicon MPX 100 processor just as volume control for the monitors, it has the same amount of static going to the output, no matter what i do on the board. It's as if the board is cranked to max volume, but it's turn all the way down. The noise is also in my mic inputs no matter the volume. All this happens when I run the power form a Dell power adapter. I have two of the same, and both give the same results. It's a 90w-AC brick adapter that sends 19.5v 4.62A(4,62A) DC. So I'm very confused. Any of you sound engineers know how to get rid of this? I have a feeling this has something to do with grounding from what I've read, but I'm still VERY confused.