I recently obtained an external crossover that I can't find any information on. I'd like to consider using it for my son's first speaker-building attempt. The unit was made by M & K Sound, Inc. back when they were located in Beverly Hills. The Model number is "Mil-K X1" Bass Extender, and it appears to have been customized to work with Magneplaners. Sadly, with M & K out of business, and nothing about this unit on the MK site or on the net, I'm afraid that I won't find anything on the unit. I've sent an e-mail to Ken Kreisel at the old MK site, but don't know whether I'll hear back. Anyone here ever deal with one of these?