Yamaha @PET RP-U100 personal receiver Measurements part 2
Fig.4 Yamaha RP-U100, spectrum of dithered 1kHz tone at -120dBFS (top) and -1LSB (bottom), with noise and spuriae, 16-bit data (right channel dashed).
Note also that extending the measurement bandwidth to 200kHz in this graph reveals the presence of a high level of ultrasonic noise, due to the D/A converter's noise-shaping. The RP-U100's noise floor is actually a little higher in level than what would correspond with true 16-bit performance, but I'm surprised that Yamaha didn't low-pass-filter the analog output to get rid of the noise peak between 100kHz and 200kHz.
The receiver's D/A linearity error (fig.5) is respectably low for what must be a low-cost part. But with the highish level of ultrasonic noise in its output, the waveform of an undithered 1kHz tone at -90.31dBFS (fig.6) is obscured.
Fig.5 Yamaha RP-U100, departure from linearity, 16-bit data. (Right channel dashed, 2dB/vertical div.)
Fig.6 Yamaha RP-U100, waveform of undithered 1kHz sinewave at -90.31dBFS, 16-bit data.