Sound Problem

Hi,
I've had my U-Mix Control Pro for about 10 months now and just recently the sound quality has been poor. I play music from iTunes on my speakers and it sounds fine. As soon as I go to mix the sound becomes very crackly especially with the bass. Through headphones plug into the controller it is even worse. I've tried different headphones as well would could it be?
Thanks.
I've had my U-Mix Control Pro for about 10 months now and just recently the sound quality has been poor. I play music from iTunes on my speakers and it sounds fine. As soon as I go to mix the sound becomes very crackly especially with the bass. Through headphones plug into the controller it is even worse. I've tried different headphones as well would could it be?
Thanks.