Looking first at the analog stages, the output impedance of the unbalanced sockets was pretty much to specification at 57 ohms, while 0dB at 1kHz corresponded to an RMS voltage of 2.018V. Frequency response was flat throughout the audio band, with a faint hint of lift (0.1dB) at 20kHz and a lower roll-off point of –2dB at 4Hz. De-emphasis was within ±0.05dB from 125Hz to 8kHz, but reached a maximum error of –0.26dB at 16kHz. Crosstalk was below my measurement threshold at all frequencies.
The output stage was non-inverting; ie, absolute-polarity correct,…