1990 D-303
The D-303 is a high-end portable CD player featuring a metal casing and a high-quality output configuration.
1989
D-Z555
The D-Z555 is a high-end portable CD player designed for high-quality sound reproduction. It features a dual DAC configuration, oversampling processing, a high-quality output circuit, and a wired remote control, improving audio output. While battery-powered, it uses an audio processing configuration close to that of a stationary unit. Playback is limited to that of a standard CD player, and it does not have vibration damping. It is a high-end model that prioritizes sound quality.
Sony took portable CD design onto a more digital footing with the D-Z555.
Instead of refining the analog-based approach that shaped earlier Discmans, this model introduced a fully digital control structure and a signal path built to match the performance of small home players.
It used dual Burr-Brown converters and a four-times oversampling filter that produced clean, stable playback with strong stereo separation.
The digital framework extended beyond the audio path.
See also D-99
