The CDX-GT420IP's simple faceplate design shows that it is one of Sony's entry-level devices. Like the MEX-BT2500, the single-DIN unit features an open CD slot and a standard arrangement of six hard buttons along the bottom of the bezel. To the left of the unit's white-on-blue monochrome display, the rotary volume knob is surrounded by six buttons for selecting and controlling audio sources, two of which--Source and Mode--have stylish red backlighting. In contrast with other made-for-iPod stereos, there is no indication on the faceplate that the CDX-GT420IP has full speed or "intelligent" iPod connectivity.
As well as its as-standard, full-speed iPod connector, the Sony CDX-GT420IP is an AM/FM tuner and has the ability to play CDs and compressed disc-based audio formats such as MP3 and WMA. Its front-mounted generic auxiliary input jack lets non-iPod owners connect their media players, too. For such a simple device, the CDX-GT420IP features some impressive audio-tweaking options: In addition to its six preconfigured EQ3 settings, it enables users to create their own custom EQ curve, and to fine-tune output by adjusting the level of the low-pass filter. A separate control for subwoofer level is also a nice touch.
In keeping with its simple design, the CDX-GT420IP is straightforward to operate using a combination of hard buttons and a rotary dial. With a digital-audio disc playing, the press of a button on the monochrome display will cycle through the ID3-tag information for the current song's album, the track, and the artist's name. We like the white-on-blue color scheme of the display in darker settings, but the characters have a tendency to wash out in direct sunlight. Only seven characters are shown at a time for each entry, but the tags can be set to scroll across the display. While we like the dedicated buttons for skipping between tracks and between albums (or folders) on a disc, there is no way to browse through the songs on a disc, meaning that drivers have to search through songs or albums one at a time to get to their favorite disc-based music.