I am experiencing some buzzing/humming in my new Studio Monitors. I have the Yamaha HS50M's, connected to an Mbox2 with Monster 1/4" speaker cables. The Mbox2 goes directly to my MBP via USB. My problem is that whenever an application has focus that uses sound (such as Pro Tools, Quicktime, etc), the buzzing occurs. If I close the application trying to use the sound interface, the buzzing goes away. It's a somewhat high-pitched buzz/hum but not very loud. Definitely noticeable though if no other sound is coming through the monitors. This happened on my Macbook as well before I got the MBP. Anyone have ideas on how to get rid of the problem?