I have a late 2009 i7 27 inch iMac currently running Mavericks 10.9.5. The problem I am outlining below is not exclusive to Mavericks as it has been a problem that I have not been able to solve since before upgrading. I have a pair of Klipsch computer speakers with a subwoofer that I have connected to a Mackie Onyx Blackjack audio interface that is in turn connected to my iMac via USB. The computer speakers have a 1/8 inch jack and I have used a "y" converter with 2 quarter inch plugs that go into the input of the audio interface. Sometimes, but not always (and frequently enough to be very annoying), when I begin playback of audio through, for example, iTunes or Garageband, or if a notification sound is made, I will get a burst of static noise. With music, this will usually last a couple of seconds or so and then correct and start playing properly. When I use the computer's internal speakers or if I plug the computer speakers directly into the iMac headphone jack there is no problem. I have swapped out the "y" cable without any effect. Has anyone heard of a similar issue or have any ideas what the cause could be?