Originally Posted by FBinNY

The answer depends on the headset/top cap and stem designs. The issue is that something has to bear on the centering cone and press it without touching what surrounds it. So if the cone is under the top cap, then yes, or if the bottom of the stem is square and won't touch the top cap in lieu of a cone above, then yes again.

But some stems and touch the part below and not sit squarely on a centering cone, and that would interfere with function. This is a rare problem, but you need to check for it. If in doubt, you can always use a 1/16" spacer under the stem.