Supposedly it improves upon the detailing, separation and sound staging between the left and right channels. Basically 1 chip it dedicated to 1 channel from what I remember (I could be wrong though). Personally it was a very nice improvement over the RWA AK100 (which is supposedly better than the AK100). I intend on keeping my unit. I'm very satisfied with it. Now in regards to the pricing well I don't agree on this area (it's simply overpriced) but that still doesn't take away from it being a great DAP and an all in one solution IMO. Now for full size headphones I'd think the DX100 and Hifiman 901 would be better suited. But for IEMs you are hard pressed to beat the AK120 as a single all in one solution. Also keep in mind they significantly reduced the impedance on the AK120 so it works well (for the most part) with sensitive IEMs.
What my bruddah say