JM99- You rock! That's it!
Philip- You should work for Lexicon. That is exactly how the MC-8 and MC-12 work.
(Except that for Lexicon, it uses *the lowest freq high passed main channel as the global low pass filter for the sub*. Doesn't have to be the mains. Although it probably would be in most systems.)
Maybe that *is* how the 950 works...