Speakers suddenly became inaudible overnight?

I have PreSonus Eris 4.5 speakers hooked up to a PreSonus AudioBox USB. I've had this set up for almost a year and it has worked perfectly fine; I used the speakers on and off yesterday. Today, however, the speakers stopped working. I can see that my computer is outputting an audible signal, but the speakers are unbelievably quiet. I have every volume knob tued up to the max and I can barely hear anything even when I put my ear right next to the speaker. Here is a list of things I have checked so far: checked for muted/quiet audio output on my PC; checked both mixer knobs on my AudioBox; checked all coections between speakers, AudioBox, computer, and power outlet; checked for a blown fuse; updated sound drivers.

I had plans to do some mixing and mastering this week and this is very frustrating. Any help would be appreciated.