See if you can obtain replacement drivers by Hyperion first (er, um, good luck).
I have tried to find a Hyperion replacement driver for the centre channel on both coasts, with no luck the last time I checked, and I have now moved on to another centre channel by another manufacturer, and sadly I have given up on a Hyperion replacement.
I don't think you will find the same technology as the Hyperions, but I have not checked out this path.
Best of luck!