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At 2 ounces and 3 by 2.4 by 0.6 inches, the Rio Nitrus has design specs that sound more like those of a flash-based player than a hard drive-based one. (Unlike the official specs, these measurements were taken at the largest points on the device's curved chassis.) The player's outer rim is rubberized, making it easier to grip and less vulnerable to damage if dropped.
In terms of style, the Nitrus presents a clean, slick, mini radar-detector-like appearance, with a shiny black front and a bare minimum of well-placed buttons that make it simple to operate with one hand. A jog dial on the upper-right corner handles navigation on the backlit LCD, which has a high enough resolution (96x64) to display the advanced menu system found on previous Rio products. A red laptop-style multidirectional control in the center of the front panel handles playback and some navigation functions, while a sturdy Hold switch on the back of the player prevents accidental button activation.
No in-line remote or carrying case is included (in fact, all you get is the player, an AC adapter, and Sennheiser earbuds), and neither is offered as an accessory at this time. Since the device is meant to be toted in a pocket, this isn't major faux pas, but a thin, protective case could prevent scratches from keys and other in-pocket objects.
The Nitrus's small, light design makes it suitable for jogging, but jostling the player while it's in the process of reading from the hard drive to the flash-memory buffer can cause your music to skip and may ultimately damage the device (it has 90-day warranty). Rio claims that it is indeed suitable for jogging--and it might be--but you're probably better off with a high-end flash player if you're looking for an athletics-oriented unit.
While it lacks extra features such as voice recording, an FM radio tuner, and line-in encoding, the Rio Nitrus has everything you need for MP3/WMA playback and more. Among its onboard features are a five-band graphic equalizer with moving high-resolution sliders, as well as six EQ presets; nine midtrack bookmarks (great for audiobooks); resume and shuffle/repeat functions; a date/time indicator; and a stopwatch.
Rio Music Manager is a polished, powerful tool for transferring tunes to the Nitrus.
For loading the player with tunes, Nitrus comes with impressive syncing software that makes its 1.5GB capacity actually feel more like 10GB, so long as you don't mind connecting the device to your PC (sorry, no Macs) every few days. Rio Music Manager 2.0 offers a plethora of powerful automatic and manual syncing options. Not only can you transfer individual songs, you can sync specified playlists, albums, artists, or genres and even set an exact percentage of new music to send to the device upon each syncing session. Multiple profiles let you set up different syncs, which can be manually executed later with the click of a button. For instance, you could delete your French-pop playlist and specify that Rio Music Manager transfer '70s jazz onto the player in its place. The well-designed program has too many other outstanding syncing tweaks and stylistic touches to list here, but suffice to say that the company has broken new ground with this software package.
A note about connectivity: While the Nitrus does not show up as a removable drive, it comes with a simple app called Rio Taxi, which allows you to transfer data files of any type to the device's hard drive and subsequently onto another Windows computer running the software.
With its new line of portable players, Rio made a concerted effort to offer superior battery life, especially compared to the iPod. According to company specs, the Nitrus's internal lithium-ion cell lasts up to 16 hours--an impressive claim that our testing verified.
In terms of sound quality, the Nitrus's squeaky-clean 93dB signal-to-noise ratio competes with that of the best-sounding MP3 players. It puts out 8mW of power per channel, which drives the included Sennheisers to deafening levels and provides ample power for higher-end headphones, such as our reference Shure E3c, to reach high volumes as well.
Connecting to a USB 2.0 port, we transferred a playlist with 100MB of music onto the player in 72 seconds, for a transfer rate of 1.39MB per second. Understandably, transfer time was slower over USB 1.1, at 0.45MB per second.