How to make Korg M50 my MIDI controller in Cubase 6?

I can hook my M50 up to cubase via a usb port, and that works, but i have to change the driver from “presonus audio box” to “Generic low latency” in order for it to sound good. If i dont do this it comes out sounding distorted and very gritty. what is the best way to add the M50 to the cubase list of MIDI control devices, and how can i get rid of the terrible clipping/ grit sound. any help is appreciated, if ya have any questions, just ask. thanks!