[rustydoglim]

http://www.monoandstereo.com/2015/04/celsus-sound-companion-one-portable.html

Some highlights from the review:

Let me start by saying that the Celsus Sound Companion One portable headphone amp/USB and Wi-Fi DAC doesn`t only sound marvelous for the size but regardless of it. It even manages to compete with much more expensive bigger units - quite easily. Frankly, I was stunned by the performance levels experienced by this extremely elegant portable unit. Replacing the mid sized DACs I have had on hand with the tiny Companion One proved the latter can stand shoulder to shoulder with its bigger sized competition and perhaps even teach them a lesson or two. No matter how hard I find it to believe, the Companion One`s implementation of the ESS’s ES9018K2M DAC and the output amplification stages are apparently extraordinarily good; the sound just seem...well, kind of, mature. On a blind listen one could never guess the sound comes from a portable unit. Of course, I`m not suggesting the Celsus Sound Companion One threatens some upper class DACs but it would be fair to point out that it plays in a league well beyond its price class - period. There is nothing that would suggest its portable nature, the sound unfolds in front of the listener in authoritative and believable manner.

Also the emotional involvement factor is quite high.

Prior to auditioning the Celsus Sound Companion One, my first prejudice was: there is no way this unit will provide acceptable levels of bass quantity and quality. How wrong was I: the Companion One provides a very extended, firm, controlled and punchy bass that easily fools the listener into thinking it is being reproduced by a big (normal) sized DAC unit with a sizeable power supply section. The José James` “The Light“ track from his Blackmagic album (2010) is one of my favorite ones for many (musical) reasons and also useful for a quick test of the bass punch AND control. Obviously I am really familiar with this track and here, the Celsus Sound Companion One didn`t disappoint; quite on the contrary, it provided all the power, heft, depth AND control - as I expect from any serious DAC

Moving into dynamic classical repertoire, the “Dance of the Seven Veils from Salome” (Eiji Oue - Exotic Dances from the Opera) was again rendered with authority and a deep, powerful and controlled bass reproduction. The hall dimensions and the instrumental 3D placement/focus were clearly portrayed in all three planes and gave a rock-solid impression. The tone and timbre of all the instruments were spot-on and the subjective “weight” was comparably good. The micro and macro dynamic responsiveness was excellent, the music sounded sparkling and alive.

[giordy60]

You can affect my impressionie listening object.
after two months of testing I can say that the companion One is a fairly balanced dac, call it transparent-neutral and able to highlight several details contained in the audio files.
tests were made with HQPlayer as software + NAA CUBOX-i I somehow put the player in Ramdisk and some other I put the executable Network Audio Deamon in Ramdisk.
the rest of the system: + studio monitors and subwoofers as volume control (not always connected) volume2 the SPL, the file (+ classical + jazz music Italian) have been played at the native resolution first and then oversampled PCM 192 and 384kHz and later in DoP DSD and 64 (for the little that I could use) in DSD 128.
the dac is carved from a single block of aluminum and is closed on both sides (front and back) with glass covers, with the six side buttons (3 per side) can control all processes and various audio set-up.
I use OSX and with this S.O. It requires no driver installation, with windows will, in the box there are a number of cables to suit all the needs of connection with the exclusion of one to use with the line-out.
the dac chip used is a saber ES9018K2M
http://www.esstech.com/PDF/ES9018-2M%20PB%20v2.1%20141016.pdf
With OSX can not be the native mode of DSD but I think it can be done in windows (I have not tried)
as it regards the WIFI mode dac has two modes, a direct (direct mode) and the other is the client mode.
Direct mode allows you to connect to a companion iPhone without using a wireless router as the client mode by entering a local address to set it up, honestly I have devoted little time to use wifi (not currently interested)
is the classic giant-killing? I do not believe it to 595 euro (being sold to the same value euro / dollar) you have an object that is more than just a dac, is small in size, battery power, is transportable, has wi-fi up to 24/192 , reads almost all PCM 44.1> 384kHz 32bit and DSD64 DSD128 and, in my humble opinion and in relation to the purchase price, is fine!
It has an optical digital output line-out of free mini-jack and a headphone output.
an aspect to be reviewed (write the designer) is that the re-ignition must adjust the output volume to the optimal level of listening, it does not keep in memory the volume previously set (perfection is not part of this world) but it could be a what you want.