I have an audiobox USB connected up as per diagram but when connected to the PC the T8 just rumbles ridiculously loud, I have to power it off, there is nothing that sounds like the output from the PC. Is it broken have I not connected it right? Everything works fine with just my E5's, I would just like a little more bass. I have a little usb ground hum but nothing this loud. The T8 cannot be powered on with the PC. Please advise.