[General Accessories] vectron:
This is a Review of Cozoy Astrapi Hi-Res USB OTG dac/amp. http://penonaudio.com/COZOY-DAC-AMP.

Also, since Cozoy is still working on their official website, you can visit their FB page for the latest updates: https://www.facebook.com/pages/Cozoy/1531647370419283

In my recent review of FULLA usb dac/amp I was very clear about not being a fan of "jack of all trades" devices, but it did get a bit frustrating when that usb dongle turned out to be a "master" of only one trade connected to my laptop, and I wasn't able to get it to work with my smartphone. The same story happened with E10k where you have to jump through hoops to connect it to your smartphone while using external power supply and splitter. With E18, I found its sound to be less transparent and device itself to be too bulky for a pair up with smartphone. When it comes to Beyerdynamic A200p (rebranded Astell & Kern AK10), it was getting down to a more manageable size with a true "jack of all trades" functionality, but sound was a bit on a cold digital side, footprint was not as friendly to attach to a smartphone, and proprietary cable connection to the unit was getting loose all the time. Sooner or later we all come to a conclusion that nothing is perfect, but one company came out with the most elegant all-in-one solution I have ever seen. In this review I would like to share with you about Cozoy Astrapi USB OTG dac/amp and how it performed in my testing.

Arrived in a small and very sturdy white carton box, it has a lot of "Apple" appeal from outside with a very minimalistic labeling of the company name on the top, model name on the side, and even Made for iPod/iPhone/iPad around it. There is also a brief info with general instructions, basic spec, list of accessories, and vague drawing of a design on the back of the box. There was no mentioning about internal components to shed a light about the type of DAC and amp used in the design, and no mentioning about USB OTG support for Android devices or USB support for use with PC/laptop. Usually companies like to over-exaggerate functionality of their product with marketing hype. Instead, here it was a very modest list where I had to figure out myself from clues of lightning connector (for Apple compatibility), micro-usb to micro-usb (USB OTG for your Android smartphone or tablet), and micro-usb to usb (connection to your laptop or PC).

Unboxing.

Basically, these 3 cables are the only included accessories, but cables itself were of a high quality. It was nice to see included micro-usb to usb cable, though in theory you can use any smartphone micro-usb cable for connection to your PC/laptop, while other cables had a unique design to accommodate smartphone connection. I don't have any iDevices to test Cozoy connected to iPhone or iPad, but had no problem testing it with my Galaxy Note 4 and S5 where I assume the included micro-usb to micro-usb cable enables direct USB OTG functionality without a need for an adapter. I was especially pleased with a solid connection of this cable to Cozoy Astrapi and my phone - nothing is more frustrating than a loose cable connection that going to affect digital audio stream.

Accessories.

The moment you take Astrapi out of the foam cutout in the box, you will instantaneously fall in love with this tiny gadget. I don't think I ever used a phrase "fall in love" in any of my previous reviews, but it's an absolutely truth when I was holding this feather light 8g stick with a dimensions of 52mm x 16mm x 6mm resembling a thumb drive. With solid aluminum alloy housing, the design is very clean with just micro-usb port on one end and 3.5mm headphone jack on the other end. Each end has 2 tiny screws with a rare 5-point star torx head. The side of the body toward headphone jack has two indentations for an easy grip, very good idea since a slick aluminum finish can get a bit slippery. Also, the back has a quality metal clip with a durable spring. A bit puzzled at first with a purpose of that clip, I realized later how convenient it was to clip it inside of my jeans pocket with a smartphone connected to it in a pocket and with an easy access to headphone jack of Astrapi facing up.

Design.

As I mentioned already, Cozoy Astrapi is truly a jack of all trades being able to support external USB connection to a laptop/PC, USB OTG connection to Android phones, and Lightning connection to iDevices. Since I don't have any Apple devices, I'm just going to assume it will work as expected since I have verified it with two other connections where it worked flawlessly.

Starting with a connection to my laptop, there was a little hiccup until I realized that you can only use Astrapi with USB2.0 port. I verified it on 3 different laptops running WinXP, Win7, and Win8, and it was consistent where Astrapi wasn't recognized connected to USB3.0 port but worked without a problem connected to USB2.0. Also, due to internal DSP chip and some protocol handshaking (I assume), I experienced a 5 second plug'n'play delay once you connect the device. Since I have on-screen volume bar indicator enabled in my Thinkpad laptop, it was easy to see when connection was established once a volume bar came up on the screen indicating a new volume scale. The volume adjustment in Cozoy Astrapi is based on output gain level steps with 3dB/step for a total of 16 steps. And to make it even more interesting, once you raise the volume to the max level, HO output of Astrapi turns into LO which indicates that internal amp was disabled in favor of pure DAC output.

Using my various full size and IEM headphones for testing, I was very impressed with a sound improvement over my noisy laptop HO output where Astrapi exhibited a black background and clean sound with no static interference. I would consider sound signature to be nicely balanced with a great level of transparency. But one enhancement that made it stand out the most was the improved width/depth of the soundstage. The depth of staging was on the same level as E10k and FULLA, but Astrapi width was better than E10k though not as wide as FULLA. The improvement in retrieval of details was on the same level as E10k and A200p, while FULLA was still a bit ahead of competition. With Cozoy Astrapi you can also hear a sound gaining an extra layer of texture and improved layering/separation of instruments with some airiness effect. Connected to my laptop, I was able to use Astrapi as an external sound card which came very handy on one of my laptops where I have a broken HO jack. Even so I have other USB dac/amp devices, they are all too bulky while Astrapi felt like an extension to a cable.

Next was a pair up test with my Galaxy Note 4, something I was really looking forward to. Similar to connection with laptop, there is a slight delay when you connect Astrapi to micro-usb port of your smartphone. Right away it’s recognized with a notification message of “usb device connected”, but it takes about 15-20 seconds before it gets self configured and you hear a sound from Astrapi output. In parallel, I was still being able to use HO output of my Note 4, very convenient while switching back’n’forth for headphone sound comparison. Consistent with laptop performance, a sound opened up with a wider and deeper soundstage, a slightly better retrieval of details, and a more linear non-distorted performance as I raised volume to the max. Now keep in mind, I'm comparing it to the current Galaxy flagship phone, Note 4, which has an excellent sound performance to begin with even from HO. Thus a sound improvement, with an exception of staging, was only marginally better. This will be probably common with other brands flagship phones, but for majority of other people who use basic cheaper Android models or who use their older Android phones as DAP for streaming - Astrapi will introduce a higher margin of sound improvement. Even with Note 4 at the top of the volume level from HO a sound was getting distorted, but with Astrapi it was not an issue!

Where I found this DAC/amp to absolutely shine with a smartphone was when paired up with external amp. Without a single doubt in my mind, a synergy of Cozoy Astrapi with either C5 or E12A was significantly greater than paired up directly from HO of the phone. In addition to an improved and more 3D soundstage, the output power of external amp added more finesse to a sound, making it more balanced and enhanced across entire frequency range. Also, it improved the tonality, making it more organic and smoother. I didn't notice any difference when I raised phones volume to the max which supposed to put Astrapi in LO mode. Either way, I found the performance to be equally great at any volume level. Comparing to HiFimeDIY, which is Android only DAC, I found Astrapi sound performance with external amp to be on a similar level, though soundstage was better with Astrapi. Also, I found Astrapi micro-usb cable connection to be less finicky, while HiFimeDIY always gave me issues with disconnects.

FULLA, E10k, Astrapi, and HiFimeDIY

Overall, I was actually quite happy with a fact that Cozoy Astrapi turned out to be a jack of all trades. The convenience of this super slim and lightweight aluminum stick being able to work with any smartphone, iOS or Android, as well as Windows laptop - was simply priceless! There was no need to use any USB OTG adapters or splitters, no need to power it up with external battery, and no need to secure it with a rubber band to keep the micro-usb cable from moving or disconnecting - it was a simple plug'n'play, always recognized by my phone. The same with my laptop, no need to install any drivers or to configure anything - as long as you use USB2.0 port it was a simple plug'n'play. I have tested a number of usb dac/amp devices, and each one had its strength and weakness. None of these devices have an identical set of features where you can just focus on sound quality for direct comparison. Instead, some have analog volume controls while others gain switch and bass boost, some might have a dedicated LO while others support both USB and USB OTG, some might only work as USB dongle with laptop while others support both Android and iOS. Cozoy Astrapi had to sacrifice a lot of extra functionality in favor of a super small size that only has micro-usb and 3.5mm ports, and lower output power in order to be compatible with USB OTG without draining too much of smartphone battery. As a result, Cozoy was able to accomplish not just a "jack of all trades" device, but also a design which you can consider as a Swiss Army Knife of audio interface. It is a bit pricy at $129, but you are paying for compatibility with every phone and PC/laptop, a proprietary DSP design, and a footprint of the smallest device with external audio interface!