Overall Rating: 7.3 out of 10.0

The Good: Very light and compact, SD expansion slot, stopwatch, FM radio, clock and date, playlists, shuffles songs, one-handed control, rubber sides, and long battery life.

The Bad: Not very good build quality, battery cover slides off easily, after awhile the headphones have to be rotated a certain way to hear the music, doesn’t stay in the belt clip very well if at all when running or jogging, and the clock doesn’t seem to keep the time and date correctly.

The bottom Line: A good little MP3 player small and compact and can be upgraded to 2.25 GB of memory. Great for a starter MP3 player but not great for those wanting a lot of memory or many cool features.

Intro
Aside from their slightly different shapes, not much distinguishes Rio's street-oriented Chiba from its sports-style Cali. The Chiba lacks the Cali's armband and secure Sport Clip earbuds, but it's attractive and lightweight, with decent features. If we could have only one of the two players, we'd go with the Cali, but the choice is essentially a matter of style.

Design
The shape of the Chiba and the Cali is hard to describe. Players resemble a fancy stopwatch (and yes, that sports feature is built into them). They're both insubstantial enough to make you doubt their build quality, and the Chiba is slightly lighter and more compact than its sibling is. The street model weighs two ounces with the battery installed and measures 2.7 by 2.4 by 0.8 inches. It survived just fine through two weeks of testing, but we can't say how well it would hold up over several months. The Chiba comes in a white 128MB and a black 256MB version, both of which have black rubber trim.
Adorning the Cali is a small but readable blue-backlit LCD, which shows all pertinent song and settings information. Beside the screen are five buttons, one of which is a joystick-like control that governs all aspects of playback and navigation. The mechanism, which the Chiba shares with the other models in its line, is fairly tactile, but in some ways, we'd rather have the larger transport key of the older S30S and S35S. We also prefer the ergonomics of the Cali, which provides a slightly bigger volume button and a better fit for both righties and lefties.
The included holster is designed for shorts and running pants; we clipped it to a belt loop to carry the Chiba to the office. We're happy to report that after some practice, you'll have no problem advancing tracks and adjusting the volume without looking at the player or detaching it from your waist.
A single AAA cell and the SD expansion slot reside in the same bay; you slide out the battery to insert the card.
The bundled Sennheiser earbuds are above average but nothing special. If you're a runner, you'll prefer the Cali's more secure-fitting headphones.

Features
The Chiba's solid feature set should satisfy most users. All the basics are here: MP3 and WMA playback, shuffle and repeat modes, auto resume, six equalization presets, and control over bass and treble. You also get an FM tuner, a stopwatch, and a time/date display that updates automatically when you sync with your PC or Mac. We'd have liked a voice recorder, though. A built-in rechargeable battery would have been nice, too, but some people find swapping in an alkaline cell more convenient than recharging.
The Chiba comes with the same intuitive Windows software that ships with most of the models in Rio's autumn lineup. Loading songs and playlists, which the player accepts via a standard USB cable, was a pleasure. The Rio Taxi application lets you use the Chiba as a data drive. And a Windows Media Player 9.0 plug-in enables integration with Microsoft's ubiquitous music program, as well as drag-and-drop file transfer on Windows PCs.
The Chiba is also compatible with the Macintosh version of iTunes, so even Apple users can consider supplementing their trusty iPods with this jogging-friendly Rio.
While the 128MB Chiba holds two hours of music, stepping up to the 256MB model will gain you two more hours. And you can increase the memory to up to 512MB with SD or MMC media.

Performance
The Chiba performed as well as its competitors. It played loudly enough to largely drown out the noise of the New York City subway--an impressive feat. As you'd expect from a flash-based MP3 player, this model didn't skip once during the three times we jogged with it. The sound was surprisingly decent through the included earbuds and even better through our Sennheiser test headphones.
Rio preinstalled several sample songs on the Chiba, so you can start listening the moment you pop in the battery. After granting the included tunes a quick audition, we reformatted the memory and loaded our own high-octane playlist.
Battery life was quite good. Rio says you can get up to 18 hours. That's a slight exaggeration, but we did manage to come close, draining the battery after 16 hours of continuous play with the backlight off.

Ratings explained
Design: 8
Features: 6
Performance: 8

Design
(33.33% of the total rating)
Since people carry portable devices everywhere they go, style is a big consideration in design when picking one out. However, we also take a hard look at the player's durability, interface, size, weight, button layout, carrying options, firmware design, and LCD for this rating.

Features
(33.33% percent of the total rating)
Here we take into account connectivity and playback options, as well as the amount of onboard memory. We also consider voice or audio recording capabilities, radio functions, playlist creation, contact-list management, equalization, expandability, support for file types beyond MP3, included accessories, and other additional features.

Performance
(33.33% percent of the total rating)
This rating deals with how well the MP3 player performs, with a particular emphasis on sound quality, power output, file transfer speed, and battery life.

What the numbers mean:

10.0 (Perfect)
This exceedingly rare score is reserved for a product that is as perfect as it could be.

9.0 to 9.9 (Spectacular)
A product that receives a rating in this range scores high on all of its rating criteria. It succeeds at meeting all of its intended users' needs and has no meaningful drawbacks.

8.0 to 8.9 (Excellent)
A product that receives a rating in this range is superior in so many ways that its relatively few drawbacks are not very important.

7.0 to 7.9 (Very good)
While the strengths of a product scoring in this range certainly outweigh its weaknesses, it has some minor faults that certain users should be aware of.

6.0 to 6.9 (Good)
This range represents a product that is above average. Its strengths slightly outweigh its weaknesses, making it good for most uses but not a standout.

5.0 to 5.9 (Average)
A product that scores in this range is functional but unremarkable.

4.0 to 4.9 (Mediocre)
Products in this range are below average. They fall the middle of the pack for most features, but suffer from a few additional major flaws.

3.0 to 3.9 (Poor)
You probably should not consider a product in this range or lower. There may be one or two specialized circumstances, however, that could justify the purchase of this product for a very low price for a specific demand.

2.0 to 2.9 (Terrible)
A product that receives a rating in this range scores low on all of its rating criteria. It does not satisfy any of its intended users' needs and has no meaningful strengths.

1.0 to 1.9 (Abysmal)
A product in this range should never have been produced. This product has no redeeming qualities and worse, may actually harm you or your productivity.