Impressions in the following,
I managed to get my hands on an AK240 at a local headphone shop in Beijing. The owner was an avid fan of Taylor Swift and Chinese opera so that's basically what I listened to all afternoon. With my HE-500's plugged directly into the AK240, the overall sound was very clean with absolutely no background noise whatsoever. Compared to the other DAPs I managed to try out, the signiture of the AK240 was dead neutral. However, I found the sound of the AK240 to be a little less dynamic than the HM901's, and a bit sterile overall. The AK240 had the widest and deepest sound stage I had ever heard from a DAP, and at times felt a bit small sounding and/or distant compared to the HM901's. Resolution and detail retrieval matched the HM901's. Based on what I've heard, the AK240 would easily fair better with IEMs with its expansive sound stage and overall lack of background noise and coloration but the dynamics and presentation of the HM901s won me over as the better sounding DAP. It's a great DAP, and probably the closest thing to IEM perfection, but in all honesty, I don't think the AK240 is worth the $2000+ price tag (in my sense of economics, thats like 4000 Mcdonald's hamburgers). Those dual Cirrus Logic CS4398's are monsters though.
I already own it, but still, what headphone shop in Beijing has it?