As noted before, REI was designed to be used with even the most sensitive in ear monitors available. The output voltage of 1Vrms at 32 Ohms does reflect that it will not power more demanding full-sized headphones. It is made to be used on the go and what’s more mobile than an earphone? So it does make a lot of sense to me, that Cozoy has put their effort in designing what eventually became the REI. A DAC with dead silent noise floor that cuts back on power.
This is exactly what you will get. REI has featured a pitch black background and absolutely no hissing with all the playmates I have introduced it to. All you will hear from this little gem is undisturbed music. You will get a wonderfully large expanded soundstage stretching in all directions, giving you a great impression of the stage. Though it might not reach as far as some other higher end devices it still is above average for its price. All instruments are very well positioned and precisely separated from each other with the right amount of air around them, forming a well detailed and sharp image. Bass reaches low with a great punch to it. This can be a lot of fun with energetic electronic music such as IDM, Glitch, oldschool Dubstep, Minimal and many others. Mids come along with a well formed body. They will not overwhelm you, but they will definitely leave an impression on you. Male and female voices are portrayed with a decent silk-touch making them appear soft and smooth. Highs are as crystal clean as they get. the Cozoy REI tickles out all hidden details in your music, uncovering what you might have overheard in the past. Overall REI‘s sound is coherent across the entire frequency range but with a hint of warm musical smoothness, giving a more enjoyable listening experience. Its sound is very natural and organic leaving an absolutely realistic feeling.
I have to admit that I was pleasantly surprised by the sound quality the Cozoy REI delivers. For the tiny package that is this DAC, I had expected a lot less.
Something very interesting I have noticed during my review time with the Cozoy REI is the importance of the transport. REI sounds much livelier and detailed with greater body and soundstage when I used it at work with Roon sending the audio files straight to this DAC. Compared to that, my iPhone as digital cook, sounded “held-back”. Still great but considerably worse than with a „decent“ transport.
I have also paired REI with my two favourite portable amplifiers, both from ALO Audio and both of their „Continental“ series. My king of amps – the Continental Dual Mono (with Mullard 6021 tubes), and its little offspring – the Continental V5 (also Mullard dual triode tube installed). Both amps will add the great tube sound to this little device and will give you the opportunity to run even demanding headphones with ease (Cv5 just looks bored at Abyss‘ AB-1266). With an external amp you will of course lose the hardcore pocket-ability the Cozoy Rei brings, but you will get a certain high end sound that still fits in your jacket. Though I wouldn’t stack too many devices together, because it gets bulky and uncomfortable at some point, the results are very convincing and made me go out of my comfort zone more than once.
Noble Sage – Sage has a great musical body and a very fun signature ensuring countless hours of listening pleasure. The combination with REI is one of my most favourite ones to be honest. It’s a fun and toe tapping sound that will convince with lots of details, a nice wide stage but most of them all musicality and smoothness.
Campfire Audio Andromeda – a soundstage you could dive into. Andromeda is known for the overly huge stage it produces, and REI is a great companion in that matter. Both together make a great pairing, a pitch black background with splendid speed and bass punch, great treble extension and the holographic sound of Andromeda make sure this will become a non fatiguing listening experience.
Campfire Audio Jupiter – definitely the most hiss prone iem in my collection, but nothing could be detected with REI – NOTHING. It is absolutely silent, which I can’t say for other supposedly silent devices. This combination results in a wide soundstage reaching out on all axes, with great micro details coming out from the surface. A musical signature yet bit raw sound. Very powerful and dynamic.
Noble K10 – Punchy low ends when called for that will leave you with eyes open. One of the many things I love about the K10 is its bass presentation. It is extremely well controlled and only shows up when needed without bleeding into any other frequency, definitely the best I have heard to date. Perfect instrumental separation, wide open spaces, full bodied mids and silk covered highs. This combo will get you a smooth and relaxing sound with a touch of analogue goodness. This has to be the most fun and pleasing combination of all that I tried.
Camfire Audio Vega – Vega also is known for its unique bass presentation, though it does reach very low with incredible impact, I still prefer the K10’s way of portraying low end notes. Vega’s bass is looser and does get into other regions where it doesn’t belong. This Campfire brings a very harmonic, organic and realistic sound to your ears. Though REI does not have enough power to make Vega really sing this combination is very enjoyable. But I prefer Vega out of a decent amplifier or a powerful DAP.
To be honest, I don’t have any other DAC/Amp in that price range except for Chord’s Mojo. Mojo definitely is the audiophile component of the last year. It shook ground like no other gear ever before. Mojo (500$) of course has a few advantages over REI, like multiple in- and outputs as well as its own battery and a higher output voltage (3Vrms). Mojo’s output power (volume) can also be set on the device itself. You can easily use Mojo as your centre of a HiFi system with all its digital inputs. The knod for portability definitely goes to REI. Strapping Mojo to your smartphone will result in a bulky package whereas REI’s incredibly small footprint and light weight won’t be noticed in your pockets.
When we look at sound alone REI does not have to fear this giant. The uber-resolving Mojo does beat REI when it comes to details but to my ears Mojo is less lively than its competitor. REI has more blood in its veins, meaning a fuller body and a more pleasing sound signature. Soundstages are similar but REI’s background is darker and hissing is absolutely not given, whereas I can hear Jupiter go nuts with Mojo. Layering from both devices is about the same and instrumental separation is pretty much equal with the REI being a tad in front. I personally think REI outperforms Mojo for what it was made. An add on DAC for your smartphone, whereas Mojo is more like an audiophile Swiss army knife with the same purpose, but REI simply does this job better than the Chord.
Taking everything into account I’d still give my vote to Mojo though, simply because it offers more inputs, has higher output power that’s even enough for some vintage 600 Ohm AKG’s, and the recently introduced piggyback module Poly can turn it into a real high end portable roon ready streaming device.
The 600$ AK70 of course is a completely different species. But when you have REI connected to your smartphone you essentially have a digital high resolution audio player that’s capable of the exact same things as the offerings from Astell&Kern, Cayin, iBasso etc. and even more. The AK70 is definitely warmer sounding and less resolving than the Cozoy. REI’s soundstage is taller on all three axes. It’s better pronounced in terms of a cleaner sound and coherence, in comparison the AK sounds a little congested and muddy if you will. The REI/smartphone „DAP“ will also give you the possibility to install any app of your liking and using your mobile data to stream TIDAL or any other service when there is no WiFi around.
I have enjoyed my time with REI a lot, and I am looking forward to trying out many more ear- and headphones with this tiny DAC/Amp. If you’re in for a new super portable DAC to turn your smartphone into a high res capable, WiFi enabled audio player with high end sound, REI might just tick all your boxes. The 550$ that REI might set you back are definitely of higher value than some one box solutions from DAP companies out there.