The ZP120 digital amplifier is the brawn of the Sonos wireless music-streaming system. About the size of a few hardback books, the amp pumps 55 watts per channel-—enough to power the largest stereo speakers—using the same technology that keeps satellites from overheating. Instead of a traditional power supply, which always provides the same high voltage, the ZP120 delivers only what the amp needs at the moment. The trick for Sonos was developing filters to shield the audio signal from stray frequencies produced every time the power supply switches voltage. $500; sonos.com
Sounds like a nice technically green product, But i don't think i want to dish out the 500 big one for this. There's nicer amp's out there without the fanciness(Is that a word?)of this. Not realistic for me with that price tag.
The Sonos ZP120 is great little piece of equipment. I reviewed this wireless digital amplifier a few months ago and I was amazed about the clarity of sound it delivers. Marty from http://www.home-theatre-systems.net/