Just a reference point... I have some Middle Atlantic Edit Center desks (ELURG), and I find their overbridge height to be perfect for M3ti's and similar sized speakers (any of many near-field monitors, for example) with similar driver arrangements. It's 8" above the surface of the main desk. I don't know if an overbridge is an option for you (seems like it would be with a built-in desk unless it's too shallow), but I like the ones on the Middle Atlantic Edit Center desks because they give me quite a bit of room to move speakers around. At any rate, I'd wager you're shooting for something very close to 8" (unless you happen to be an NBA center :-)).
