Well, headroom can be thought of (simplistcly) as a wider range of frequency and dynamics one could use to record a sound. Think of it as a limited amount of dimensional space one could put a sound in (again this is a simple explanation).

Imagine a 3D space that is 44,100 cubic feet as opposed to one that was 48,000 cubic feet. The larger space would allow you to capture more of the sounds artifacts and resonance - more character.

Just becuase something was recorded with more headroom doesn't mean that it will always sound better. There is less headroom on the Orch. I board, but there is also a larger variety of sounds that are related to the Orchestra.

Also, while there is more headroom on the Orch II board, there are less Solo strings and as I said earlier, the strings on the Orch II card have a more prominent vibrato which is a little more irritating to me.

Remember, this is just my opinion. You should really try to audition them yourself as I did to come to that conclusion. You may find that you end up believing opposite of what I do.

The Infamous EPU.