I have an Mbox 2, a macbook, and a stereo pair of KSM141's. I'm getting a bunch of pops and hissing from them. I tried a different pair of 141's and got the same thing. I tried a pair of SM57's and they were quiet. I thought there was a problem with the phantom power, but I tried a pair of Avlex C131's and they were fine. Any thought?