Classé Omega Super Audio CD player Measurements part 2
Fig.5 Classé Omega, 1/3-octave spectrum of 10Hz at -120dBFS, with noise and spuriae (from top to bottom above 10kHz): DSD SACD data, 24-bit LPCM data (right channel dashed).
As implied earlier by the fig.4 spectral analyses, the Omega's linearity error was very low down to -100dBFS, though with a little more noise than normal (fig.6). This graph was taken from the balanced outputs using CD data; spot-checking the linearity using SACD data gave the same result. The waveform of an undithered 1kHz tone at -90.31dBFS was essentially perfect (fig.7).
Fig.6 Classé Omega, balanced left-channel departure from linearity, 16-bit CD data (2dB/vertical div.).
Fig.7 Classé Omega, waveform of undithered 1kHz sinewave at -90.31dBFS, 16-bit CD data.
Distortion was a little higher than I expected, and, unusually, worse from the balanced outputs than from the unbalanced. Fig.8, for example, shows an FFT-derived spectrum of the unbalanced output while the player decoded CD data representing a full-scale 50Hz tone. The second (100Hz), third (150Hz), fourth (200Hz), and fifth (250Hz) harmonics can all be seen. Though the third harmonic is the highest in level, this is still negligible at -74dB (0.02%).
Fig.8 Classé Omega, unbalanced spectrum of 50Hz sinewave, DC-1kHz, at 0dBFS into 100k ohms (linear frequency scale).