Amazing Sony CDP-591 CD-Player. CD player equipped with newly developed pulse 4D/A converter. The D/A converter consists of a high-density linear converter system, a 45-bit noise-shaping digital filter and a pulse D/A converter. The Pulse D/A converter consists of a current source and an electronic switch. It expresses music waveform by switching two values of 0 and 1 at high speed. By this, the amplitude level is always constant and changes only in the time axis direction. The PLM (Pulse Length Modulation) wave is output. By passing it through a low-pass filter, unwanted high-frequency noise outside the audio band is removed and music waveform is obtained. To reduce quantization noise in the audible band up to 20 kHz, the pulse D/A converter is equipped with a multi-stage noise shaping operation that employs 64 times oversampling and the Sony Extended Noise Shaping method. Oversampling reduces quantization noise in the audible band by increasing the sampling frequency. Noise shaping reduces quantization noise in the audible band by feeding back the requantization error to the input side when the number of bits is reduced. These technologies ensure a high dynamic range. The pulse D/A converter operates at 45 mega pulses per second, and it completely eliminates differential non-linear distortion, glitch, and 0 cross distortion, which were difficult with conventional methods. The CDP-591 uses a single-mode pulse D/A converter. A single pulse D/A converter provides a 4D/A output that outputs positive-phase and negative-phase LR signals.