Again, I’m unfamiliar with XDCAM. However, if you must transcode with software use Compressor. Make sure to turn Frame Controls on in the Frame Controls tab of the Inspector. Then choose Best for the 3 quality settings you’ll find there. Compressor will take a long while (probably) to do the cross-conversion, but the quality will be very good. Try a short clip to judge for yourself. It may also be possible to simply drag the clip into your ProRes seq and render there (again, with the highest quality settings in Seq Settings>Render Control). Search for transcoding, and other advice will probably pop up.
John
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