Outboard DACs

Chord's debut Mojo was the most impressive portable battery-powered USB DAC/headphone amp we'd had on the bench thus far [HFN Jan '16] and, on the basis of power output alone, remains the class leader besting the likes of Astell&Kern's CA1000 [HFN Mar '22]. At full volume, and with a peak level (0dBFs) digital input, the Mojo 2's output is already clipped (+15.5dBV or 5.95V), but backing off reveals a 'clean' voltage output of +13.5dBV (4.7V), realising power output(s) of 37mW/600ohm, 540mW/32ohm and a full 630mW/8ohm [blue, black and red traces, respectively, inset Graph]. Even at substantial outputs, distortion remains very low, increasing from 0.0001-0.002% (unloaded) to 0.0009-0.021% (10mW/32ohm, 20Hz-20kHz) once loaded.

Chord's under-the-bonnet updates all hit the mark. So, the Mojo 2 offers lower noise than the Mojo – the A-wtd S/N is significantly wider than before at a massive 114dB while hiss and hum remains very low at –101dBV to directly benefit very sensitive headphones. The Mojo's output impedance was always low at ~0.75ohm but is a little lower still in the '2 at ~0.5ohm (20Hz-20kHz), resulting in a mere 0.1-0.2dB loss into a standard 32ohm load while further improving its 'resilience of response' into low and variable headphone impedances. Otherwise the frequency response is determined as much by Chord's WTA digital filter and DAC as the incoming sample rate. PM