Given how no one has gotten their hands on them, it's impossible to know what DAC it uses unless Sony tells us outright.
I have a sony phone (xperia s and xperia u), they either use qualcomm DAC or a ST Ericsson DAC, depending on the phone model.
Honestly I don't think xLOUD makes any difference, it's not like the phone is all the way up to need the extra power. and clearbass?...I'd rathe buy an IEM with good quality bass than rely on some voodoo circuitry/EQ. (i.e. don't believe the marketing)