Irig HD Sound Quality Degrading When Plugged in For Long Periods

I have had a consistent problem with my irig hd since I first got it. It tends to work fine just after I plug it into my computer (running it through Logic X). However, when I leave it plugged in for more than half an hour or so, the sound quality seems to slowly deteriorate, getting increasingly muddy, until the signal isn't audible at all despite registering on the faders in Logic. Unplugging doesn't work unless I leave it unplugged for several hours before using it again. I've witnessed this on a mac pro, mac mini, and macbook pro. At first I thought it was an overheating issue, but the USB isn't always hot when I remove it. This shouldn't be happening, especially not on devices and software branded as "professional".