Chord Electronics Hugo2 transportable headphone amp/DAC

Headphone amps and amp/DACs
Chord Electronics Hugo2
Chord Electronics Hugo2 transportable headphone amp/DAC

When Chord Electronics released the first-generation Hugo headphone amp/DAC in 2014 it started a revolution in more ways than one. First, the Hugo proved that a headphone amp the size of a paperback novel could not only compete with but also potentially surpass the performance of full-size desktop or rack-mount components. Second, the Hugo introduced many audiophiles to a whole new way of thinking about DACs and the digital filters used in them—the Rob Watts way, as we’ll discuss in more depth in a moment (Watts’ digital audio design concepts had been used in earlier Chord products, but none with the sonic sophistication and widespread appeal of the Hugo). Even though the Hugo was relatively expensive it became a huge commercial success, largely because enthusiasts deemed it to offer good value for money in light of the extraordinary performance it offered. Now, Chord is back with a better and even more capable new Hugo2.

What’s different and better about the Hugo2 vis-à-vis the original Hugo? Just about everything.

Chord sought to give the Hugo2 more power, lower distortion, and reduced noise floor modulation as compared to the original Hugo. Accordingly, the Hugo2 puts out 1050mW at 8 ohms (up from 720mW at 8 ohms in the original Hugo), distortion rated at 0.0001% @ 1kHz/3V (down from 0.0005% in the Hugo), and a 126dB signal-to-noise ratio with “no measurable noise floor modulation” (an improvement on the 120dB dynamic range of the Hugo). Chord says the Hugo2 amplifier features a full Class A “discrete OP stage integrated into the DAC output amplifier and filter” that is “capable of 5V RMS and peak output currents of 0.5A”. The Hugo2 analogue amplifier section also features second order noise shapers said to “reduce distortion with load(s).”

In turn, Chord has dramatically increased the capabilities and all around sophistication of the Hugo2 DAC section relative to the original Hugo. The first-gen Hugo’s DAC was a 4-element pulse array design with a digital filter offering about 26,000 filter taps; in comparison, the Hugo2 DAC is a 10-element pulse array design whose digital filter offers a stonking 49,152 filter taps (second only to Chord’s famous flagship DAVE DAC, whose filter offers a staggering 164,000 filter taps).

To appreciate Chord’s focus on digital filter design and on providing very large numbers of filter taps, it helps to read some of Chord Consulting Designer Rob Watts’ white papers on digital audio. Both the mathematics and the technical concepts behind Watts’ design philosophy become pretty dense and complex in a hurry so let me instead provide a scaled-back laymen’s interpretation for you. In a nutshell, Watts maintains that—for purposes of accurately reconstructing analogue audio waveforms from digital audio signals—he could get just as much resolution from CD-quality files as from ultra high-res files (albeit with a higher noise floor), provided he could use a digital filter with an infinite (or near infinite) number of filter taps. If you stop to think about it for a moment that is an astonishing assertion and one that potentially points the way forward for future high-performance DAC designs. Naturally, in the real world there is no such thing as a filter with an ‘infinite number’ of taps, but when you consider that most commercially available DACs use filters with taps numbering in the hundreds, the Hugo2’s filter system with 49,152 filter taps represent a huge step in the right direction. In particular, the Hugo2 does an exceptionally good job of accurately rendering transient and timing-related details in the music, including cues that contribute to the perceived three-dimensionality of sounds.

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