I have a DA but I don't use it for color sanding so I can't help there. When I color sand over orange peel I start w/ 600-800 grit, water and dish washing soap till I cut the peaks down some; I am careful not to use 600 if I am getting close to the valleys. Post 800 grit I move to 1000, 1200 and then 1500 before buffing. If I am out of a grit I just go to the next higher one. Sometimes I buff after 1200 grit. If my clear has orange peel then I spray one additional coat of clear to give me adequate film thickness to sand out the orange peel.