Just sat down and listened to my AD8620 mod'ed X3, Nano 7G and DX50, volume matched to within 0.5dB of each other (it is impossible to match any closer since all three has digital volume control). Here are some quick impression:
Soundstage (wide -> close): DX50 > X3 > Nano 7G
Texture (thick -> thin): X3 > Nano 7G > DX50
Control / tightness: X3 > DX50 > Nano 7G
One thing that struck me early on is that DX50 sounds more gainy and bright than most DAP I have. The three way comparison really explains why - it is because DX50 is really thin on the mid and upper bass, which in effect emphasizes more on the treble in the overall presentation and makes it more edgy than it should. On the other hand, the slight hollowness also gives DX50 an excellent soundstage. IIRC, these are kind of opposite to what I have heard on the stock X3. I think I still prefer my mod'ed X3 the most. Though it is easy to tell that Nano 7G isn't quite as good as DX50, I think it actually has better balance as well. If only DX50 has a thicker mid, it would have been really great. Just wonder what opamp DX50 has on the headphone-out and maybe they are worth modding as well.
Hallelujah! Clieos I haven't seen eye to eye in all your reviews but this is the same impression I'm getting. Some parts of the DX50 sound is great, but the mids sound thin to me! Would the X3 be a great improvement in this aspect? Clarity of vocals is better on the X3?