Confused about compound clips and quality

Working on a music video. Making the jump from FCP 7 to FCP X finally. I have a sequence that is 1920x824. All of the actor sequences have been laid in. Im adding performance footage that is 4k (4480x1920). Everything is transcoded to 422. I synced some audio to each 4k clip for reference in a new compound clip. When I bring the 4k footage into the timeline it is framed smaller and says its at 100 percent. I have been scaling snd transforming to my needs. I just realized that I may be losing quality?? Is this correct??? I didn't use multicam for client reasons.

Thanks