The AK100 is at heart a wonderful digital source player, deeply engineered in a unique fashion. It's best seen as a portable high resolution 'CD player', masquerading as an MP3 player. I used it as such through its headphone outlet and got spectacular sound quality from high resolution 24/96 and 24/192 digital recordings. It's very well made and finished and it works well too...
....casual listening in a quiet room made obvious the AK100 has a darkness to its silences and a sense of silky smoothness, almost warmth. I found myself winding the volume right up, the sound was so clean... I switched to a pair of Sennheiser HD650s and it all got much better, greater dynamic scale, firmer bass and more extended treble becoming obvious in particular.... the message is the AK100 is way above a normal portable in quality terms, in another league in fact.
Moving onto a Marantz SR8002 receiver in an AV system with Martin Logan Electromotion electrostatic loudspeakers up front made clear that the headphones do not reveal the AK100's potential .... its smooth, almost silky quality was obvious, characteristic of digital done properly, meaning not CD. Violins hung in space and were clear and stable, and also clearly separated from each other... swapping over to to a direct optical connection bought out greater low level filigree detailing and a stronger sense of depth and space to the sound stage... the same was was true of Rock, kick drum sounding firm, brushed cymbals shimmering with fine detail... This is a top quality, high definition music player that can be connected up to a hi-fi through its headphone output [or digital output]. The AK100 is no ordinary portable, that's for sure.
.... idiosyncrasies apart the Astell&Kern AK100 is an astonishing player, with fabulous sound quality and an amazing spread of ability as a source. It's a must have in fact.
The AK100 produced exceptional results for a portable player. It has massively greater dynamic range, lower distortion and negligible jitter than typical portables, measuring a well as a high quality stand-alone DAC. It's a portable hi-res player that approaches the limits of what is possible.
Reviewed by Noel Keywood, Editor of Hi-Fi World.