I measured the Marantz Model 40n with my Audio Precision SYS2722 system.1 For the digital-input measurements, I used TosLink data and the HEOS app on my iPhone to play back test-tone WAV files on a USB stick plugged into the rear-panel port.
The Marantz’s single-ended line inputs preserved absolute polarity at both the loudspeaker and headphone outputs. The volume control operated in accurate 0.5dB steps, and the maximum gain was 40.6dB at the loudspeaker outputs and 40.7dB at the headphone output. The power amplifier stage offered a fixed gain of 24dB. The input impedance at both the line inputs and the power amplifier inputs was 15k ohms at all audio frequencies.
The Model 40n’s output impedance at the headphone output was a relatively high 320 ohms. The loudspeaker output impedance, including the series impedance of 6' of spaced-pair cable, was 0.1 ohm at 20Hz and 1kHz, increasing slightly to 0.12 ohm at 20kHz. The small-signal bandwidth was extremely wide, the response into 8 ohms (fig.1, blue and red traces) down less than This graph was taken with the volume control set to its maximum (“100”); the excellent channel matching was preserved at lower settings of the control. The extended ultrasonic response meant that the Marantz’s reproduction of a 10kHz squarewave featured very short risetimes (fig.2). Commendably, no overshoot or ringing was visible. The bass and treble controls offered a maximum boost and cut of close to 10dB (fig.3).
