PS... Make sure your S90 ES is set to MIDI IN/OUT = USB if you are connected directly to your Mac with a USB cable... (just making sure we haven't mis...

If I understand you correctly, the Yamaha USB-MIDI Driver 1.3.2 is working and is communicating with your S90 ES MainStage will (among other things...

Okay, I purchased an S90-ES last year and I had no problem using it as an controller for MainStage. I have not since upgraded to OSX Yosemite (10.10.3...