You need to plug it into the Green Speaker / Headphone Out Jack on the back of your computer, not the Speaker Input.
If that does not solve your issue, then open a support request in your https://my.presonus.comaccount so a support tech can further assist you.
It was plugged into the headphone out jack on the back of my computer, like I said, I had perfect sound for almost 2 weeks out of it. I meant to say headphone input, I just incorrectly reffered to it as a speaker input because that's where you plug speakers into.
Anyway, the speakers seem to have completely broke now as they don't produce any sound whatsoever.