Currently Being ModeratedRe: Can I connect a Yamaha S90 keyboard to my macbook pro via USB to access Logic's MIDI capabilities?Feb 3, 2014 3:17 PM (in response to worldwyn)
Shouldn't be any need to use the AMT8, if the S90 has USB.
I seriously DOUBT you will need drivers, either.
Just create a new device in Audio Midi Setup, and the next time you open Logic, you should be good to go.
Weird that the AMT8 doesn't seem to be working, but once again, use above info for setting up the AMT8 while in Audio Midi Preferences while you're at it, and then you have BOTH options.