Default USB-OTG External Soundcard

Hi there iam trying to use my external USB-DAC (Audioquest Dragonfly) over the USB-OTG Connection and so far i atleast achieved somehow to playback tracks using "USB Audio Player Pro Trial & USB Audio Recorder Pro Trial" but iam facing some serious problems while doing so.

If i activate the lockscreen(pressing powerbutton) to turn the display of, i can't reactivate it anymore, it keeps playing the music but the screen doesn't turn on again.
After 1-2 Minutes it reboots itself without asking for the PIN etc...




Anyone else facing those issues, and is there a possibility to use the external Soundcard without third-party apps?
How about the leaked 4.4 build? I heard USB-Audio is fully functional in 4.4 without third-party apps.


Thank you