USD $99.99 @ Griffin
Griffin’s Twenty audio amplifier lets you play audio from iTunes and AirPlay-enabled apps to an existing set of speakers using your Airport Express and Apple’s AirPlay wireless protocol. The result is a solution that is an easy to setup streaming audio system powering your speakers via a low-profile, all-digital amplifier.
AirPlay works by streaming audio from your iTunes library or AirPlay-enabled apps directly to your Airport Express. Twenty takes the digital output of your Airport Express, amplifies the audio, and then sends the sound through your speakers.