Editor's note: Given the similarities of the 604 and the 504, portions of the Archos 604 review have been used in this review.
Archos's 04 series includes a model for everyone. The midrange 504 may not be the thinnest gadget around (it has a 2.5-inch drive inside), but it sure can store a lot of data. Available in 40GB ($350), 80GB ($400), and an amazing 160GB ($600, shipping soon) capacities, the 504 fills in the storage void left by the 404, the 404 Camcorder, the 604, and the 604 Wi-Fi, which all max out at 30GB. Measurable bulk and pricey 160GB version aside, the do-it-all 504 is an awesome A/V performer.
At 5.1 by 3.1 by 0.9 inches and 11.11 ounces, you're definitely sacrificing the sleekness found in the 0.5-inch-thick and 9.3-ounce 604 series (read the 604 review). This gadget fits better in a bag than in a pocket (though it's only a tad larger than the Cowon A2). Otherwise, the physical design and GUI are the same as for the 604. You still get a removable battery that lasts longer than the 604's, a built-in mono speaker, and a dazzling 4.3-inch display. Notably, though, there is no built-in kickstand, a must-have feature if you're into hands-free viewing.
The 504's brushed-metal casing is extremely scratch resistant, and even its gorgeous 4.3-inch, 480x272 pixel/16-million-color wide screen can withstand some punishment (though it does attract fingerprints). Like the AV500 series before it, the primary controllers line the right-hand side of the screen, though this time around the buttons are more intuitive. Unlike the AV500, which featured sets of unlabeled buttons of varying sizes (think Tetris), the 504's buttons are uniform and marked. Personally, I didn't mind the AV500's controls, but the 504's are much better.
Each button is designed to be pressed in either the left or the right direction, including the special set of diagonal buttons that act as page up/down when browsing and skip/reverse about 30 seconds when playing content. The controls work in harmony with the GUI, with context-sensitive menus and submenus appearing on the expansive screen mapped to a specific button. Despite its simple control panel, the excellent Cowon A2 can be a bit more difficult to use, though the 504 is very difficult to operate smoothly when you're in the dark. Backlit buttons would have rocked.
Speaking of the GUI, it's been revamped, with slick animated icons and a more modern feel. Backgrounds as well as text and accent colors are customizable, and everything from the audio playback screen (with album art) to the photo thumbnail page (where pics magnify as you scroll over them) is refined. Archos manages to pack lots of info onto the screen without making it feel crowded.
The main menu includes Video, Music, Photo, Browser, Resume, TV Scheduler, VideoCorder, and AudioCorder options. Even without an FM tuner, the 504 is feature rich, though you'll need extra accessories to record video and audio (more on that later). You do get a good voice recorder out of the box, and the built-in mono speaker is decent, though not as crisp as the A2's stereo speakers.
Video playback is where the 504 shines. According to the specs, it's compatible with MPEG-4 ASP up to 720x480 at 30fps, AVI file container with MP4 file format, WMV9, and protected WMV. Unlike the Cowon, it's not DivX certified, and it doesn't play MPEG-2. However, many of our DivX files played without a hitch. You can also download plug-ins that will let you play H.264 and MPEG-2 files--they will be available soon at about $10 each (there's mention of AAC and AC3 support, too). Though it doesn't cover the same ground as the Cowon, the 504 can handle your files, which in part will be transcoded via Windows Media Player, the de facto jukebox for the Archos. Though we'll comment on video performance later, the 504's screen is amazing, and video controls are quite responsive.