The operating principle of “Real-Sound Processor” had been made in public on the Japanese specialized magazine named MJ, “AUDIO TECCHNOLOGY” by Mr.Yasui throughout 1971. He just drought out this concept as ” Impedance Correction” for speaker. Yasui-san was a senior amateur researcher and a person of authority of semiconductor linear amplifier. At that time he got into the conclusion that only the pursuit of improving the static characteristic of power amplifier could never bring the superior sound. And also he set up the importance of amplifier’s dynamic characteristic including the actual movement of speaker to get musical sound. But still right now, after more than 40 years passed, we regard his view point as an excellent insight and much further a relevant challenge for the present “audio-technology”. Sorry to say, we should recognize we only know the improving the dynamic characteristic of the system consisted of amplifier and speaker might be an extremely important factor for getting superior sound quality. For that matter, we are not able to reach at an effective measuring method to be fixed the dynamic behaviors and also expose the real relations between the characteristic and our hearing. We suppose, so many reasons might exist. But one of the major difficulties of analysis of the dynamic characteristic would be speaker itself. Needless to say, speaker is the transducer which converts some electric energy to kinetic motion. But if we were to say frankly, this transducer would be a collectivity of imperfect characteristic for being driven by amplifier. How fluctuant the impedance frequency characteristic is, you know. Yes it might be quite simply the hard load of amplifier. But also you should remind one more thing, “Counter-electromotive Force” of speaker. The motion of speaker is started in the magnetic circuit or voice-coil of the unit by the current be flowed from amplifier on Fleming’s left-hand rule and at the same time this motion raises up counter-electromotive force in the voice-coil by Fleming’s right-hand rule. It is true that amplifier drives speaker, but would be the fact that speaker affects amplifier by this counter-electromotive force. And this counter-electromotive current returns to the amp via the speaker cord, making it difficult to drive speaker in accordance with the input signal. And this current causes negative effect especially on the traditional semiconductor linear amplifier. Since the transfer function of semiconductor is poor in linearity compared to tube, this type of amplifier inevitably needs correct the static characteristic by performing negative feedback circuitry. But this negative feedback makes the amplifier stage vulnerable to the counteraction, counter-electromotive current from speaker, causing complicated phase delays inside of amplifying stage. Needless to say, this physical phenomenon hurts the sound quality of the audio system including amplifier and speaker.