What electronic subwoofer x-over?

Anyone have recommendations of good electronic subwoofer x-overs to mate with dynamic speakers? Is Janis Subwoofers still in business? Where can I find subwoofer electronic x-overs on this site? Anybody heard of MT Audio of Sweden? Please, no snide or condescending remarks about my interest in such "distortion creating devices"!. Thanks.
HSU Electronic Crossover
I have a barely used sub control unit from Paradigm that I amy be willing to sell. Email if you you have any interest/want more info.
I'd look into the Bryston.