In theory yes with a good midi controller you can program it to control pretty much anything. However from my experience and understanding ( I have an A6 as well) the midi features are somewhat limited on the A6. I use dedicated Midi controllers with no onboard sounds The Roland A70 and M-Audio Axiom 49. By the way since you own an A6 If you have not seen this site check it out...
http://www.wohmart.com/a6/