I tried to :
- format my microSD
- use an other microSD
- re-download the ISO
- use an other tool to flash the microSD
Nothing changed...
There's my debug data :
http://pastebin.com/THpnxxav
I think the ISO on this website is not the correct one.
On the download page it is written "v0.3-beta" for Raspberry Pi 3, but the one I get is "RuneAudio_rpi2_rp3_0.4-beta_20160321_2GB"
For the RPi3 the ISO should not be different of the RPi2 ?