can clip+ rated at 15mw be able to drive these at all??
i don't understand how this works??
The 100mW you listed, if I'm reading the specs right, is the power handling capacity. In order to determine if you can use your headphones out of a particular source, two of the important specs to look at are impedance and sensitivity. For the XBA-3, they are listed at 12 ohms and 108dB/mW.
I'd go out on a limb here and say that these will be easily driven from most sources, especially portable players. However I don't own these or the Clip so I can't speak from experience.