Here are some photos of the DX50. I apologise for the focus issue on the last image - I hadn't noticed until it was on my computer. Hopefully the rest of the images will do it justice.
http://imgur.com/a/zTnhF
I will review it at some point, but I do not want to rush it. I will say however, that the amp is very powerful. With my AKG K550, it seems to be just as loud as the E12, which is no slouch for power. It resolves a lot of detail, and keeps things more balanced than the E12. However, the E12 holds together better at higher volumes, where the DX50 can get very harsh - almost muddled. If I had to describe the DX50's sound with one word, I'd say 'Sharp'. Fortunately, it is not as aggressive in this 'sharpness' as the ODAC, which to my ears (and through the E12, feeding into the K550) is offensively sharp. Highs are almost painful to listen to. The DX50 has well defined highs, lows and mids, but without that offensiveness the ODAC gives off (this is my opinion of course). The ODAC does sound fantastic feeding my Marantz PM6003, which powers my Monitor Audio BX2s. The E12 sounds smoother, and would be ideal for me in situations where I don't want to be attacked by the music. The E12 also represents a wider soundstage, as far as I can tell.
Compared to the J3, it lacks the 'warmth' of the Cowon sound, though again, not in a negative way. The sound is more detailed and clear, but not dramatically so, and this is fair enough, for both the J3 and DX50 cost around the same (in the UK anyway. I paid £180 for the J3, plus shipping, whereas I paid £175 plus slightly more shipping for the DX50). For me this was intended to be a replacement and not so much an upgrade, but an upgrade it is. The J3 still works, but I think I'll give it to my dad so he has something high quality to listen to all his music.
I wrote more than I meant to, but alas, this is only scratching the surface. Keep an eye out for my full review, coming somewhen soon.
No, it does not allow you to do that. However, if you are meticulous with your tags and folder structure (the DX50 allows for more than two folders deep, unlike the X3 I believe) then you can use the Directory View, which does the same thing - annoying it isn't built in, but it's an easy workaround and might help with future DAPs, if you intend to move your music between them.