Sony Xperia SP Output Impedance?????? how to find it.

[naveen]

Hi, I'm planning to buy Sony XBA-3 IEM.
 
The problem is that I'm going to use them with my SmartPhone (XPERIA SP).
 
As you all know that XBA-3 has low impedance 12 ohm.
 
I can't buy XBA-3's until I know about my Xperia SP Output Impedance
 
I don't know the Output Impedance of my XPERIA SP. Can anyone tell me what is the output impedance of SP????