I would think you may be out of luck if you are running HOB. With canisters, you can always extend the discharge and diffuse it.
Have you thought of attaching a media pad or sponge to the HOB output to help soften the discharge?
this is prob ur best and cheapest soulution. I just use a sponge over the return and it slows the water down to a trickle. Get a black sponge so it wont stick out or do wht i used to do and cover the spong with java moss.
http://www.aquariacentral.com/forums/showthread.php?t=115551