I mean quite literally that the amp (at least on paper) is more powerful, has a lower output impedance, and is made by an amp manufacturer. The DAC and that stuff is up to you, but CIEMs cannot technically be driven as well via the AK120. Portable phones, yes, but with nearly 4Ω output, the AK120 isn't quite as able to put the full resolution of a song into your earphones- unless they are high Ω earphones.
That's not to say that there are not issues with the DX50 output. I have no idea. But iBasso make very good amps and I assume the DX50 is no slouch. I will be reviewing one a bit later so I can chime in from a position of experience. For now, I'm talking about on paper, but on paper, unless lies, nearly always pans out in terms of getting the actual output up to snuff.
Ah, okay I understand now. Personally, the lower output impedance is a none issue for me because I find the AK120 to pair nicely with pretty much everything I've thrown at it. With regards to power, I totally agree - I'd love to have more room to play regarding dynamic range etc. The amp in the DX50 is good, still unsure if I think it is better than the AK120. As a package, it still gives up some quality(IMO) but so far not enough to justify keeping the AK120. G/UI wise - both are rather fluid, with the AK120 slight edging it out. Load times are faster, and rendering is as well on the AK120. With refinement, I can see the DX50 equaling the fluidity and stability of the AK120. Too early to tell, but I'm very happy with the sonics of the DX50 thus far. Going to try it line out to my Pico Power to see how much I can improve its performance. If anyone is wondering the DX50 stacks nearly perfect ontop of the Pico Power.
Edited by Greed - 9/10/13 at 5:18pm