Roth Audio's Music Cocoon MC4 is a world-class tube amplifier that also happens to have an iPod dock on-board, combining the warmest, smoothest amplification with the most popular source in the world. It's also equipped with an S-Video output to send any video content from your portable audio/video device, a 3.5mm input accommodates virtually all MP3 players and laptops, and even traditional RCA inputs for an audio device such as a CD player. This means that regardless of the source unit, the MC4 can handle it, which immediately makes it more useful than simple docking device for the iPod.
The Music Cocoon has been designed for use with the iPod (hence the dock on the top of the amplifier which charges and interfaces with your iPod), any portable audio device (that's why there is a 3.5mm socket on the back of the amplifier), any device which outputs audio to a 3.5mm jack (e.g. a laptop), or a CD player (that's why there is a pair of RCA sockets on the back as well).