Thanks for your comments, Bob. I'm thinking I could hook up the subwoofer to one set of speaker cables from the amp, and then after running through the high pass filter in the subwoofer that signal can go from the subwoofer to the Apogees' woofer inputs. I could then run my second set of speaker cables from the amp directly to the Apogees' midrange/tweeter inputs (the speakers are bi-wireable). Does this sound do-able?
Now to find a subwoofer that will do this with minimal effect on the sound of the main speakers.
Now to find a subwoofer that will do this with minimal effect on the sound of the main speakers.