Let the hive mind of Engadget get that for you.
"For a long time I have been searching for a portable device where I can store all of my CDs in MP3 format and stream the songs wirelessly to my HiFi system. The portable device must I've tried FM transmitters, they all suck. I don't want a docking station. Any help? Thanks!" have a display so that I easily can scroll through the playlists (I don't want to use a TV or monitor). I suppose that there must also be a second device that is connected to the HiFi system that would receive the wireless streams from the portable device.
and it has extra battery life :D
http://images.google.dk/images?hl=da&client=firefox-a&rls=org.mozilla:da:official&hs=4LC&resnum=0&q=battery%20grip&ie=UTF-8&oe=UTF-8&um=1&sa=N&tab=wi