HeadAmp Pico Power Portable Headphone Amp Grey

Video review here: [...]I bought this during the original pre-order from HeadAmp, years ago. It is very beautifully made and the design is very well thought-out.The switches are tiny, and not easily bumped. The volume control is short and firm, but smooth to turn. With three gain settings it is possible to get excellent sound with even sensitive earphones. I have used it with planar headphones from Audeze, HiFiMan and MrSpeakers with no problem, as well as the Sennheiser HD800. Even with a Chord Mojo, I feel it is a bit better with high-end headphones than using the Mojo direct. The sound is neutral, with good performance and detail in the bass, mids and treble. The treble is pleasantly smooth as the distortion is very low, both audibly and as measurements show online.The main negative is that when the batteries run out you have to change them. There is no charging through the amp. The screws on the battery cover are easy to lose as well, but the amp comes with spares.