Review: The Cozoy REI – What a surprise!

Disclaimer: Cozoy sent a free sample of their Cozoy REI DAC/Amp in exchange for this review. The unit does not have to be returned. A shout out to the Cozoy team, as they have been very responsive. Many thanks! The pictures used are taken by me (sorry) or come from Cozoy. 

About Cozoy

Cozoy is a relatively young brand, being formed roughly three years ago. They have already introduced the world to a hand full of different products like Astrapi, Aegis, Takt, Hera and REI. The following is posted on their website:

Cozoy was incorporated in 2014 with a simple vision – to strive for ultimate sonic reproduction and functionality. Our designs are crafted with selected metals and components, fusing with leading designs.“

Today we’re looking at their super small DAC/Amp, the REI.


REI’s key features are native DSD support up to DSD256 and PCM decoding up to 32/384. It has got an ultra low ripple linear power supply built in and features six arrays of discreet regulators to deliver clean sound. It is kept down to the very basics: one input and one output. You can hook REI up to your source via one micro USB input. The 3.5mm single ended output goes to your head- or earphone. Simple as that. This little gem has been designed to be used with even the most sensitive in ear monitors, so there should be no background hissing. REI appears to be made out of aluminium and only has one round play/pause button on top of it.

REI does not pack a battery in its tiny housing and sources the needed juice straight from your smartphone, PC or Laptop. Those of you who are looking for measurements can find Nathan’s detailed RMAA results over at

Specifications at a glance:


micro USB


3.5mm TRS

Output Voltage

1Vrms @32 Ohms

Total Harmonic Distortion


Signal to Noise ratio


Bit rate supported

up to 32bit/384kHz

DSD rate supported

up to DSD256 (11.2MHz)

Cozoy – REI

When REI hit my doorstep I was more than surprised by the size of the package. I did expect something bigger, though I already knew it was a very small piece of equipment. It still baffles me how small the device is compared to other units out there. Included in the package are three different IC’s (Lightning, OTG and USB) to hook your new DAC/Amp up to whatever source you want it to feast from. The package overall is very solid and well made. You will also get a voucher for some DSD samples and an information card about the Relisten Player app.

I have mainly been using it with my iPhone playing TIDAL HiFi and at work as DAC being fed again by TIDAL HiFi and Roon. For the sake of the experiment I have also tried bypassing the internal conversion from my Astell&Kern player via USB output to REI, but since the AK does not allow volume control when an external DAC is connected I could not listen to anything with this little chain. One of the best things about REI that might get overlooked when searching for a new portable digital to analogue converter is that it pairs up nice and easy with iOS devices. No need to add a tingly camera connection kit to make the iDevice deliver digits to it. A nice change of pace.

One thing I have noticed rather quickly about this DAC is that it gets relatively warm after quite little time. Not worrying hot, but still warmer than your regular DAP. What also has to be noted is that it can be very sensitive to volume changes. If you found a comfortable listening volume I suggest you carefully try to add another portion or just stick with the one you have acquired. It has happened to me that one click above resulted in considerably higher loudness. This has to be respected especially with in ears with higher sensitivity .

Most of the time I have used the Cozoy REI with my iPhone 5. Hooking both up is as easy as it gets as the supplied Lightning cable does its job fairly well. Simply connect both devices together and pick your poison when it comes to playback software. I’ve been exclusively using TIDAL HiFi, since I don’t have any music stored on my phone. Of course I do have many files sitting on a micro SD card, but Apple does not want your phone to have an expansion slot.

Since REI receives power from the transport it is connected to, said device will lose juice a bit faster than usual. The Cozoy team suggested that I’d burn in the unit for at least 100 hours so that the capacitors settled in properly.

So I did exactly that…

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4.3/5 - (21 votes)

A daytime code monkey with a passion for audio and his kids, Linus tends to look at gear with a technical approach, trying to understand why certain things sound the way they do. When there is no music around, Linus goes the extra mile and annoys the hell out of his colleagues with low level beatboxing.


  • Reply April 28, 2018

    Nick Rath

    Awesome review as usual! Have you used to this with the 64 audio a18 at all? Do you think it would inject some nice warmth into them with a nice bass boost?

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