Hi!
I'm running my Prophet X through an Apogee Duet (all current firmware and software) into Logic Pro X on a mid-2012 MacBook Pro.
Hearing a high frequency hum (about 600) through my monitors.
Also, audio stops when USB is connected. I went through all sorts of 9to5 Mac steps to set up my PX as an external instrument; note info shows, as well as track input levels, but still no audio out.
1/4" outs work fine - as long as USB is disconnected.
I'm ready for good advice.