Update: Added disclaimer (2015/07/09).
Disclaimer: COZOY graciously supplied Astrapi for the possibility of a Headfonia review. I paid nothing for it.
Subject: COZOY Astrapi
High praises have been heaped on this little guy. It's no wonder: Astrapi is tiny, beautifully machined, and powerful. On paper, Astrapi is a headphone amp/DAC every audiophile should desire. It does iOS, Android, and PC/Mac. But in reality, it is just another audio device that sacrifices almost every thing in pursuit of volume.
Let me break it down:
1. Astrapi's noise level is treble, or greater, that of the iPod nano or iPhone 6.
2. At its very lowest volume setting, Astrapi will be too loud for sensitive-eared listeners that use sensitive earphones.
3. Astrapi's ability to drive quality signal into sensitive, low-Ω earphone and headphone loads is, at best, on par with older iPods.
In other words, I'm calling BS yet again on The Pro Audio Web Blog (hereafter PAWB). PAWB reckon Astrapi is best with earphones and that headphones sound 'insipid'. Astrapi holds its best-quality (closest to no-load) signal through low-current, high-impedance headphones such as the DT880. It begins to fall apart when driving loads of less than 32Ω. PAWB know shit.
Other than higher theoretical maximum power output Astrapi is no match for today's iPod nano or iPhone. High-impedance headphones fare better. Still, in objective (but not professional) testing, Astrapi offers nothing but more absolute volume for HiFi headphones; and if we're going to get subjective, a sound signature that may, or may not, jive better with your tastes.
To be honest, I expected far better. But I've tested far worse. Here's hoping that the 2nd generation Astrapi will be better on every front. For now, I recommend Astrapi for those stuck in the EU who need more volume from their phones, or who are on the fast track to hearing aids. As well made and beautiful and compact as Astrapi is, adding one to your iPhone bulks up your portable getup and offers no improvement beyond placebo.
BTW, I believe that Astrapi comes from the same brains/brawn that gave us the Shozy Alien, about which I heaped both praise and condemnation here, and whose RMAA measurements are here. In every non-haptic metric, Alien is Astrapi's better. In fact, Alien is one of the better-sounding, not to mention better-measuring DAPs out there.
The following Rightmark Audio Analyzer tests were conducted through this equipment.
Source: COZOY Astrapi through Apple iPhone 6 and iMac 27" (2012)
ADC: Lynx Studio HILO LT-TB
Computer: 2012 27" iMac
Cables: 1,5m Hosa Pro 3,5mm stereo to dual 3-pin XLR (around 8$)
NL - no load
SM2 - Earsonics SM2
ES7 - Audio Technica ES7
DT880 - Beyerdynamic DT880/600
16-bit & 24-bit TARGETS and loads
16-bit results summary
24-bit results summary