Pioneer has rolled out four new sound systems for the iPod and iPhone. The new Audition Series XW-NAS3/-K system features a top-mounted dock, a double isolated frame for improved bass response with less cabinet resonance, a 2.1-channel dynamic digital amplifier, component and composite video outputs, compatibility with Pioneer’s AS-BT100 Bluetooth adapter, and a down-firing subwoofer. It will be available in April in black or white and will…