Now Kensington has released FX 500 ($50), which for $20 more changes three primary features the FX 300 design: you now get iPod screen and control access through a medium-thickness clear plastic panel, a second speaker, and considerable additional bulk. Like FX 300 and Portable Sound Laboratories’ iMainGo, it’s technically device and iPod-agnostic because it uses a headphone plug rather than a Dock Connector to connect your iPod, but it…
