There used to be a service called Jammit that would license multitracks/stems to help practice or learn or whatever. They had Images and Words, Awake, ACoS, FII, Metropolis pt2 and Octavarium's official stems uploaded. They would have uploaded more but they unfortunately went out of business before any more of the stems were released, although due to label reasons I imagine we only missed out on 6DOIT and Train of Thought.
