Integrated Amplifiers

The 371’s alloy sidecheeks are not simply decorative for they also act as the heatsinks for its L/R power amplifier stages, the latter trampling all over the 100W/8ohm and 200W/4ohm spec. by delivering a very generous 2x140W/8ohm and 2x260W/4ohm. This +2.7dB power increase is indicative of MOON’s stiff PSU regulation but it also explains the ‘neutral’ dynamic headroom whereupon the MOON 371 supports 140W, 254W and 395W into 8, 4 and 2ohm loads under dynamic conditions. Maximum current is 14.1A (<1% THD/10msec) but this is limited to 10.3A/105W into 1ohm [see Graph 1, below]. That said, it’s resilient enough to handle most likely partnering speakers. Distortion, too, is very low at 0.00025-0.003% (re. 10W, 20Hz-20kHz) and steady with level at 0.0004-0.0008% from 1W-100W (all re. 1kHz/8ohm). The response is very flat at –0.14dB/20kHz and –1.5dB/100kHz, with some treble roll-off into lower loads (–0.25dB/20kHz into 2ohm). With the ‘Offset’ at 0dB, gain is a sensible +31.5dB while the A-wtd S/N ratio is a generous 90dB.

Tested at a volume of ‘74dB’ (2V RCA preamp output from a 49ohm source impedance), the ES9039Q2M-based DAC board benefits from a low <10psec correlated digital jitter, although there is some low-rate phase noise. The A-wtd S/N ratio is a very healthy 109dB while distortion is low at 0.0003-0.001% over the top 20dB of its dynamic range [see Graph 2] and linearity is good to ±0.2dB over a 100dB range [red trace]. Response and alias rejection are determined by the fast minimum phase filter, reaching out to –0.0dB/20kHz, –0.3dB/45kHz and –0.7dB/90kHz with 48kHz, 96kHz and 192kHz files, respectively. PM