Originally Posted by MichaelW
You can but there is little point. The systems will be less secure, heavier and you will still need a threaded headset.
You may want to look for a quill stem with a front-loaded clamp; that would be useful for fitting bars, esp modern ones with funny shapes.
If you find one, let us know.
One company that is always good for stems/bars is 3TTT.
Profile makes a 1" quill stem with a 26mm clamp diameter and two bolt front loading clamp. I think its called ther H2O series.