I'll second a look at the Schlappi stuff...they've put out a line of truly ill-behaved, nasty modules that specialize in spectacular sonic wreckage. Another couple that might be worth your attention: Moffenzeef and Noise Reap.
Seriously...go BIGGER. I know the idea of some little box that obliterates hearing is sort of a harsh noise scene "thing," but if you take this on up into a more typical case size, then you can start to assemble something of a harsh noise "ensemble" under your direct control. In "I Dream of Wires" (probably the long edition) there's an incredible extended bit of Keith Fullerton Whitman doing a Eurorack set using only a pink-noise generator as the initial source and a LOT of parallel processing chains to screw with it. Definitely worth a look...