Yes, it is a tough decision. For example, if you like warmer, fuller sound, then N7 should be a better choice but even it is more expensive, it is no way comparable with detail, cleanness of DX260. Again, DX260 amp is not bad at all ... in fact, it is one of most powerful DAP at its price range (I found that it is even more powerful than iFI Gryphon - not based on spec, but AB comparison). However, if you are looking for more colourful, fun sound (which could mean different things to different people) out of the box, then it may not fully satisfy you.
p.s. Btw, I also own a Sony WM1AM2 ... in my opinion, don't expect to get the 'best' sound from just one integrated device. Just like the old days when I was listening to Hifi, separated DAC, pre-amp, power amp almost always give better sound than an integrated amplifier.