Airplay crashes when playing music

[Gnom]

Software
XBian version: XBian 20150407-0
XBMC/Kodi version: (shipped with XBian)
Overclock settings: default

Hardware
Device type and model: Raspberry Pi Model B 512 MB
Power supply rating: 1A
SD card size and make/type: Sandisk 4 GB
Network (Ethernet or wireless): Ethernet
Connected devices (TV, USB, network storage, ...): Projector via HDMI and amp via analog audio

Log files
Last lines I get before crash occurs. I turned on the airplay and audio specific debug in the debugging menu, but it doesn't give any additional info. I'm not sure there's a way to get some more detailed log?

Code:

20:20:32 T:2815353872  NOTICE: Thread JobWorker start, auto delete: true
20:20:32 T:2781799440  NOTICE: Thread FileCache start, auto delete: false
15:57:55 T:2835858448  NOTICE: Previous line repeats 6 times.
15:57:55 T:2835858448  NOTICE: XBian : on saver deactivated
15:57:55 T:2835858448  NOTICE: XBian : on saver deactivated END
15:58:22 T:3024622608  NOTICE: CAESinkPi:AddPackets Underrun (delay:0.00 frames:2205)

Problem description:
I did a clean install of XBian, except for some minor settings (installed the youtube addon, set the network, turned some services on) it is brand new. Yet I am having a problem with the airplay function of Kodi. When activated, my iphone can see the airplay server and connect to it, but as soon as I push play Kodi crashes and restarts. It does the same if try it with itunes.

How to reproduce:
Everytime with my settings (basic XBian settings except network which is a fixed IP; ssh, smb and apache are on, and in Kodi I just set the theme to use a unicode font and installed the youtube addon but the problem was already present before).