COS Engineering is founded by three close friends who are serious about audio entertainment. With an aversion to cacophony, an aspiration for style and a penchant for simplicity, we harness extensive knowledge and experience in mathematics, electronics and communication to research and design. The objective is to offer gears featuring musicality as well as aesthetics. D1, COS Engineering’s first product, makes its debut in 2014.

D1’s clarity is of a different sort. It’s richer, wetter and more fluidic but without the harmonic padding and thickening many valve circuits will create.
Srajan Ebaen
the publisher of
…and if you’re looking for neutral, organic and overall very refined sounding d/a converter, which on top of that has extremely good pre-amplification stage, without a blink of an eye I recommend you COS Engineering D1.
Dawid Grzyb
professional audio journalist of

C O S D 1

D1, a dapper unit in cool aluminum, is a fusion of a digital-to-analog converter and a pre-amplifier. It is capable of rendering crystal clear, spacious and dynamic music and meets the demand of those with willing and fastidious ears.


The exterior of D1, composed of aerospace grade aluminum alloy which seals off electric and magnetic interference from outside, is crafted finely to embody a structure of straight lines and a single circle.


COS’s proprietary algorithm with a linear-phase delay FIR filter can up-sample original data to 176.4K or 192K, and this massive computation is handled by a powerful 3648 MMAC/sec DSP.


D1 stores digital data in a one-second buffer before converting to analog signals, under the coordination of a crystal oscillator with a jitter precision less than 1ps and a dedicated re-clocking circuitry.


Two torroid transformers power the digital circuit and the analog circuit separately, thereby eliminating possible interferences.

C O S H 1

A lot of folks choose not to own a full-fledged Hi-Fi set, especially bulky speakers, because of limited room space or preference for the inclusivity of one, and one alone, when music is played. A solid combination of a DAC and an amplifier that helps a choice headset perform would be the answer to compromising not a bit in audio quality of cherished tunes.

COS Engineering is about to introduce an audiophile-grade gear, H1, to meet such a need. Once a headset and a player for digital music (a notebook or a CD transport, for example) are at hand, H1 is all that is needed.

Coming soon!