Split audio output between USB headphones and analog subwoofer

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http://superuser.com – I have a wireless USB headset. It has good mid- and high- range quality, however lows are obviously bad. I also have analog speaker set with a subwoofer. Since I don't need to "hear" subwoofer, but rather "feel" it, I want to use my headset for music and plug in the speaker set, but only output audio with frequency lower than certain threshold. Is it possible in general? If it is, what are the solutions? (HowTos)