I'm old enough that I cut my teeth in the analog world with tape machines, 2 rules of thumb, do not overdrive anything unintentionally and you can Y all of the outputs you want but never Y an input. This sounds like something is being overdriven [turned up too high] or like 2 inputs are Y'ed together. [ 2 input processes fighting to enter the audio chain somewhere] Kind of that sound like when the snares on a snare drum rattle from the toms or loud audio. In the analog world you would look to see if you were over driving your pre's, mixer etc. and make sure you wern't clipping your monitor amp. I believe this machine was like this out of the box because I was disappointed with the audio before I installed any 3rd party software, I guess that is a good news bad news thing. I should have taken it back. My bad!!