I been reading HeadFi for several years, but never registered.
Mactire's issue with DX50 made me register. I have exactly the same issue. I bought the DX50 yesterday in Bangkok at MunkongGadget, ibasso dealer in Thailand. Reason to buy, I spend winters here but forgot to bring my Fiio e18, so needed something to drive my Grado PS500.
DX50 is nice, I liked the line out, for the money DX50 is nice. Until this morning, it went silent in the middle of a song while I was adjusting volume. FLAC file that playing was on 32Gb SD card. Same black screen that Mactire described. The screen is black, I can see it is back lit, but nothing on the screen.
Tryed all the usual, power button and volume up - unit reboots to same black screen. Remove\replace battery - same black screen. Holding down power button for 7 sec, same black screen. Connect USB charger and repeat all of the above - black screen.
Mactire says his issue with DX50 must be one off, cos Google search does not bring any match to similar experience. Well, it does now, I found Mactire's post, and ragged to post this. Why post? Because this is unacceptable! DX50 had numerous bugs when first released, we are now at firmware 1.5! Yet this machine functions like $20 mp3 player that streets vendors in Bangkok are offering on every corner.
DX50 is inexpensive, no doubt. Cost in Thailand is 8500 baht, rufly $300. It should play music, it is not too much to ask from a day.
Since Mactire bought his unit recently as well,logic tells this is a bad batch.
I will return my brick of a DX50 tomorrow morning, walk straight to Sony Center and get a ZX1. No more beta testing questionable Chinese Daps for me!