personally i dun like both xenos amps, coz X0HA is having high hissing sound but so far so good performance.
yet, X3HA is too bulky & IMO not a portable amp at all....maybe jus movable instead.
i agree xenos do improve but with comparison to so many china portable amps in HK, i would prefer the really lotsa choices in the same price range on the mkt.
for me i would sell nano, use the money for the amp & from nano to buy a 2nd hand iAudio X5/X5L or Toshiba F20 (choose according to your music listening preference) or discman....if u were considering xenos