Playing back data representing a dithered 1kHz tone at -90dBFS gave a textbook analog output spectrum (fig.4), with no level error and no spurious tones or power-supply components present. The rise in the noise floor from low to high frequencies is due to the constant 1/3-octave filter bandwidth used, and to the noise used to dither the signal. The Sony's own analog noise is below this level, as can be seen (at least in the midrange and below) in fig.5. This graph shows the spectrum of the player's balanced analog outputs, now plotted up to 200kHz, with the player decoding data representing a 1LSB DC offset. The peak between 40kHz and 60kHz is due to the noise-shaping used in the player's low-bit DAC, and there are no differences in the ultrasonic noise floor whether the filter used was "std" or "dfil-4." Note that the right channel (dotted trace) is almost 10dB quieter at low frequencies than the left, which is about the best I have seen from CD replay.

Fig.4 Sony SCD-1, spectrum of dithered 1kHz tone at -90dBFS, with noise and spuriae, 16-bit CD data (right channel dashed).

Fig.5 Sony SCD-1, spectrum of -1 LSB with noise and spuriae, 16-bit CD data. (1/3-octave analysis, right channel dashed.)

The SCD-1's DAC linearity on CD replay (fig.6) is also superb—as the same DAC is used for SACD replay, I assume this fine performance will also apply in that case—while the player's low analog noise floor and excellent linearity mean that its representation of an undithered 1kHz tone at -90.31dBFS (fig.7) is also textbook. The three discrete voltage levels and the Gibbs Phenomenon "ringing" at the bit transitions in this waveform are clearly evident.

Fig.6 Sony SCD-1, CD left-channel departure from linearity (2dB/vertical div.).

Fig.7 Sony SCD-1, waveform of undithered 1kHz sinewave at -90.31dBFS, 16-bit CD data.