Yes any controller. It has on board styles and sounds

for example you could use it with:

1) midi keyboard (can be split for chords on left, voice on right
2) more than one midi keyboard (upper/lower)
3) midi accordion
4) midi guitar
5) midi bass pedals (for changing chords) whilst singing/playing non midi instrument

The main problem with MidJay is the lack of quick access buttons often associated with arranhgers (style banks, voice groups etc)- but the new MidJay Pro has a nice looking touch screen which may make it easier to use than current MidJay.