Same problem here. I updated from Mavericks to Yosemite on an early 2008 iMac and installed the newest monkey/driver. Monkey does not start, keeps jumping in the dock. When the driver is installed and the X3 is connected, I get a kernel panic and the mac crashes. In the panic log one of the first entries showed coreaudio. With no driver installed and X3 connected or driver installed and X3 not connected the mac works fine. I hope you'll find a solution soon.