The CHARLiE 2.1 is a two-speaker set-up (2) with a subwoofer (1).The CHARLiE 2.1 system comes complete with the RothDock meaning - thanks to the wireless receiver built into the base of the CHARLiE subwoofer - a wire-free connection between your docked iPhone and iPod and the speakers/subwoofer - they can be up to 15m apart. In addition, with the USB input and the auxiliary input, this system will work with anything you like, but specifically computers, laptops, etc., where your music is likely to be stored. The runaway success of online music services, such as iTunes and Spotify, means more and more music is "trapped" on flash drives and hard drives. This all makes fine sense... until you listen to tunes via the speaker systems generally found built into the sexy-looking, but increasingly compact Mac, PCs and laptops. The resulting audio from these built-in speakers tend to come ladled with ASBO-deserving treble, search in vain for convincing midrange, and are utter strangers to the valley town known as Bass. "Enter stage right CHARLiE 2.1".With the quality audio reproduction in mind the CHARLiE 2.1 System would not sound or look out of place for those who mix there own tunes at home or indeed in the pro arena - a true compliment to any audio software packages.The RothDock supplied is also officially both a "Made for iPod" and "Works with iPhone" certified product, so there is no need to adjust your iPhone settings to "airplane mode". Turn It Up.SpecificationsPower Output: 25wFrequency Response: 40hz-20khz(±2db)Harmonic Distortion: ?2%Signal To Noise Ratio: ?75dbInput Impedances: Aux 10k ohmOutput Impedance(L&R) 8 ohmOutput Impedance(Sub) 4 ohmTransmitter Distance: 10m