Where do you find modules for theta dreadnaught amps?

I've been looking here for a little whilst and maybe it's the nature of my amp being old but no one is carrying modules for the dreadnaught 2. I'm sure there are shops and people that have them! I want to make my 2 channel amp to a 5.1 so I can get rid of my rotel and clear up some space. If any of you know of any place that have second hand cards I'd appreciate it