I finally gave up and bought the Logitech Z5500s and absolutely love the sub and control unit with my old Klipsch speakers. The Logitech speakers lack the brightness of the Klipschs, contributing to the "muddy" sound people associate with the Z5500s.
This system rocks and is very clean - no hum, even with the amp cranked and idling.
Also, even music sounds great with the Klipsch individual speakers and Logitech sub and control unit. Love the remote, too.
I wish I would have done this a long time ago.