Review: COS Engineering H1 – Just ’cause

Disclaimer: The H1 in this review is on load directly from COS Engineering. The H1 goes for around €2,500. You can find out all about it on

Finding an integrated DAC / headphone amp as restrainedly designed as the H1 isn’t easy. Finding one as restrainedly designed that also performs can be a bugger. Which, of course, makes getting excited about the majority of modern integrated DAC/headphone amps another bugger. Lynx’s HILO has spoiled me. It’s spoiled me because it converts everything digital to analogue, and converts everything analogue to digital. No questions. After a short evaluation I ponied up. Gladly. Its warmish, rich-ish headphone output is reminiscent of an iPhone 4. For me at least, that means lights out for practically every mains DAC that comes across my desk.

The H1, however, is an anomaly, in some ways evoking HILO’s best DAC bits, in many ways tripping beyond them.

Not sound

COS designed an easy-reading manual that explains basically everything in simple, clear English. Better yet, its hardware interface follows suit. A long press of the oversized attenuator wakes the H1. Another long press puts it back to sleep. Hard OFF/ON is controlled from the rear. Rotating the attenuator ups or downs the volume by jumps of 0,5 dB. As far as digital attenuators go, it is one of the best I’ve tried: easy to turn, wobble-free, smooth. It is also impossible to miss. Attenuators this large, this ergonomic don’t exactly grow on trees.

In fact, because it is so damn big, you can be stumbling drunk and still use it. Strangely, the H1 can skip a half step in favour of a round number, 1dB instead of 0,5dB. The H1’s only other notable anomaly is the nomenclature behind its digital input menu. It goes something like this: USB, OPTICAL, RCA, XLR. It should be: USB, OPTICAL, COAXIAL, AES/SBU. USB can be switched from 1,1 to 2,0, and appears to perform flawlessly when plugged into my MacBook Pro, but, like so many USB devices, triggers my 2012 iMac. Measurable performance between the two differs by as much as 20dB SNR and 10dB DR.

By the way, check out how thick its chassis is. I measure almost 4mm, or almost twice as thick as the HILO’s chassis. It is the most solid integrated chassis in a mains DAC/headphone amp that I’ve yet tried, which is a testament to the effort COS put into making the H1 solid, tough, and engineering it for the long haul. Its flat feet fit solidly on proper desks, and its rear input array sits in a reinforced, recessed well. That makes it nice to photograph, and protects cables in systems jammed up against the wall.

The H1 is a tank. Unlike a tank, it gets along with civilian life.



Digital Input Sampling Rate

Digital-to-Analog Converter


Total Range Accuracy


USB x1, Asynchronous 1.0/2.0; SPDIF x 1; TosLink x 1; AES x 1 Optical / RCA / XLR: up to 192K PCM 24 bits & DSD64 (DoP) USB 1.0 – up to 96K PCM 24 bits
USB 2.0 – up to 384K PCM 24 bits & DSD64/DSD128 (DoP) 24-bit DAC x 1 (up to 192Ksps, 24-bit)

192 steps by 0.5dB/step 96dB
Within ± 0.1dB

Supports 2 unbalanced headphones or 1 balanced headphone

Frequency Response THD+N

Signal-to-Noise Ratio

Headphone Impedance Full Scale Output

Line out

Frequency Reponse THD+N Signal-to-Noise Ratio Full Scale Output


Disply Weight Dimension Power

+ 0dB, – 0.5dB (20Hz ~ 20KHz)
< 0.001% (- 100dB)
(192Ksps, 24-bit, 20Hz ~ 20KHz, A-weighted, 16 ohm load, 2Vrms) > 110dB
(192Ksps, 24-bit, 20Hz ~ 20KHz, A-weighted, 16 ohm load, 2Vrms) 16 ohm and up
Unbalanced : 6 Vrms; Balanced : 12 Vrms

+ 0dB, – 0.5dB (20Hz ~ 20KHz)
< 0.001% (- 100dB) (192Ksps, 24-bit, 20Hz ~ 20KHz, A-weighted) (192Ksps, 24-bit, 20Hz ~ 20KHz, A-weighted)

128 x 64 pixels white OLED
3.5 Kg
260 mm (W) x 250 mm (D) x 60 mm (H) (boot is not included) 100 ~ 240VAC
Normal Operation < 20W

Standby 0.5W (typical)

Sound and more after the jump:

4.8/5 - (19 votes)

Back before he became the main photographer for bunches of audio magazines and stuff, Nathan was fiddling with pretty cool audio gear all day long at TouchMyApps. He loves Depeche Mode, trance, colonial hip-hop, and raisins. Sometimes, he gets to listening. Sometimes, he gets to shooting. Usually he's got a smile on his face. Always, he's got a whisky in his prehensile grip.


  • Reply March 26, 2017

    W.H. Lin

    Hello Nathan,
    As an OCHARAKU fan & COS H1 owner, I’ve to say that we both have many common preference.
    The COS H1 is a very surprising DAC/Amp. I really love its clear & bright sound. The amp part of it is quite good enough. However, the DAC part is more outstanding in this price range!!! The COS H1 is indeed a game changer.

  • Reply March 27, 2017


    I took a chance on this unit based on an early review and could not be happier. It makes every thing I have thrown at it sound great. The level of detail, tonal balance and overall natural presentation is unmatched in my experience and the dac section is really something special.

    Currently I switch between Focal Utopia, Lawton modded Th900, AKG k701, Technics EAH-T700, Noble k10au and Etyomtic ER4S and the H1 clearly brings out the best qualities of each.

    Very happy to see this unit finally getting the recognition it deserves!

    • Reply April 23, 2018

      ohm image

      Sorry this is late, but so glad you enjoy the H1 and that this review was helpful.

  • Reply May 18, 2017


    I don’t think the Vivace has a low pass filter. I believe you meant to say its the bass is slightly lighter or less impact or slightly rolled off.

    A low pass filter is an active stage or circuitry or digital filter (in a DSP, DAC, amp, or driver crossovers) meant to allow low-frequency to pass and reduce/cut off high high and mid frequencies.

    And don’t write like 6moons—it’s difficult to read with all those flowery prose that is difficult to understand. (-_-)”

    • Reply May 18, 2017

      ohm image

      I have one sentence that reads like gobbledygook. The rest is pretty intelligible. The moment I dive to 6moons levels of unintelligibility is the moment you can end my life. Permission granted.

  • Reply January 30, 2022


    How do its inputs fare? I am looking for a source to pair it with, and was wondering gow its AES + RCA inputs fare compared to USB.

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