Pros: great price, lots of connectivity options, plenty of power, DSD support
Cons: sound is smoothed, lacking minor details
Aune constantly improves their X1, current revision, released in 2014, is fourth in a row. It got new updated power supply with lowered noise, and Savy Tech's SA9027 as USB chip. New USB interface allowed DSD support and increased USB rate to 96 KHz/24 bit. Not the best numbers nowadays, but still more then OK. By S/PDIF X1 "understand" up to 192 KHz/24 bit, so if you have USB to S/PDIF converter, it can be nice addition to X1.
Outer box is made from simple brown cardboard, it's task — to protect device during shipment, but main box is hidden inside. It's made from black cardboard and looks really stylish for such inexpensive device (it's retail price $250). Inside you'll find X1 Pro itself, power supply and cord for it, USB cable (pretty good quality) and manual.
Device is made completely from metal, case is thick and solid. Due to it's shape, X1 can be placed flat or upright.
On the rear panel placed all interfaces: Line In, Line Our, USB, Coaxial and Optical S/PDIF, power socket and switch. On front panel located 1/4" headphone socket, volume knob, two buttons to chose input and output and LEDs to show selected options.
X1's strong part is lots of connectivity options. You can use it as pure DAC or as pure amp, so you aren't limited in step by step upgrading of your system.
Build quality is also good, no gaps or something like this. Volume regulator moves smoothly and dosn't produce noise.
Sound-wise X1 is more of "tasty" sounding. It uses PCM1793 as DAC and pretty powerful headphone amp, so overall sound signature is tilt toward smooth and musical representation. Sound have small hint of darkness, due to smoothed highs, so overall sound doesn't have those "audiophiliac" neutrality. It's DAC/amp with it's own signature. Soundstage is a little bit less then average, but with good headphones X1's representation is nice.
Due to big power, X1 isn't good option for sensitive headphones, but if you chose something appropriate, it will be great pairing. I like it with AKG K702 (not the greatest amp for them, but pretty good), and with Fischer Audio FA-011 Japan Limited Edition (extremely well for classic rock and live jazz).
I've also made small video to show X1