i Fi is a kind of sound box which is provided with a self matching power amplifier inside the sound box. The power amplifier is designed for promoting the speaker enclosure, due to the special matching design, so the power amplifier can effectively to promote the horn sound box, thereby allowing the user to do not need to consider the power amplifier and impedance matching.
Also because in the sound box is arranged in the front of the amplifier frequency electronic frequency divider, and each set amplifier is only responsible for a frequency of the audio signal amplification, so efficiency of the amplifier can often do some taller, distortion is also relatively smaller.
Refers to the so-called high fidelity audio power amplifier in the internal speakers, can be directly connected with the sound source and the normal work of the speaker. A number of active speakers will not only be integrated into the speaker, but also the decoder is integrated into the speaker inside, you can directly accept digital signals, which is the high fidelity audio speakers. Although literally, high fidelity audio can be considered to be must plug the speaker, but strictly said this "source" should understand the power amplifier, and does not refer to the power, because there are many need to plug in the power cord still need external power amplifier driver of the speaker, the speaker obviously do not belong to high fidelity stereo speakers.
Hope that the above remarks you can understand, you are welcome to inquire.