I recently bought an mbox2 mini. i want to buy a mixer and have found a few decent behringer models in my price range. My question is, my mbox is very limited on i/o. 1 xlr, and 1 1/4' for direct is all i have. some of these mixers, have 12-24 channels. do i need to have a matching amount of i/o to channels? or will it sync with pro tools and and whatever i set the output at on each track relate to the mixer?