Michael,
Not an expert here, but I've been trying quite a few different ways to buff urethanes in the last couple of years and I think I've finally found a system I'm really happy with.
After color sanding with 1000, 1500, then 2000 paper, I went with a Meguiars wool pad on my Makita with Meguiars new M105 compound. I've found that I really need to start with a wool pad and compound, it takes a pretty aggressive setup at first to really remove those sanding scratches. Followed that up with a Meguiars maroon foam pad and the same M105 compound. Then switched to their yellow foam pad and their M205 polishing compound. Then I used their tan foam pad on my DA polisher with the M205. Followed up with a hand glaze and some wax and it's like glass.
I know this sounds like an ad for Meguiars, but I really like the stuff. I tried the all in one system from Norton and although the results were OK, I didn't think it was quite aggressive enough to completely level a color sanded surface. I then went through a time of experimenting with all the various Meguiars products, compounds, cleaners, swirl removers, etc., but still hadn't really settled on anything. When they came out with the new M105 and M205 this year I decided to try it and it looks like I finally found a system I'm really satisfied with. Plus I only need to stock the two products and four pads.
Just be careful if you're new at this. It's pretty aggressive with the wool pad at first.

Bob