Hey Jeff,
A digital noise over the USB connection can sometimes be an issue of a bad USB cable, or poor isolation on your computer's charging circuit if you're using a laptop. The first fix is obvious - try a different USB cable, and the second would be to disconnect the computer's power supply and run only off the battery; if the noise disappears, the problem is that of noise between the charging and USB circuits on the mainboard and a new DJM won't fix that problem.
Let us know if either of those fix the issue for you.