Still portable and still loud, the iK501 still features the outrageous, square-shaped reflex subwoofer on the back of the unit, along with a pair of five-inch woofers and silk-dome tweeters. It's all juiced by a powerful internal amplifier with digital signal processing for the richest, best-sounding docking system available. Dig deeper into DSP with the thin infrared remote, fully featured to fine-tune the iPod or iPhone's music and video content. It helps to navigate with ease through the iK501 system menu, adjusting bass, treble, and aux-in options, as well as through the iPod or iPhone's menus and sub-menus. Skip forward and back, fast-forward and back, play and pause, volume, mute, and power on/off selections have their own buttons too. The rotary knob manually serves as the power and selection push button, and controller for bass, treble, auxiliary-input options, or standby mode. Standby will continue to charge the iPod or iPhone even when the system is powered down. In the dark, the knob is back-lit in blue and the display LCD screen continues to steer the user easily through the menu. A mini-jack input allows a hookup for stereo sound from alternate media, including other MP3 or compact-disc players, desktop and laptop computers, or satellite radio. RCA stereo outputs allow for even more alternative audio hookup.