[rbinck]

Even with the Niles box the speakers have to share the available power, so it would subtract from the main speakers. Also the Niles volume controls somewhat rely on having a constant volume level so that interaction does not occur. Using the receiver volume level as well as the Niles is sure to end up with the Niles and the receiver fighting each other, so to speak. I would recommend a separate amp, but you wouldn't necessarily need a second receiver as a power amp with an input level control should do just fine.