what do they mean? not all earphones have them in their specs, but how do I tell the sound quality of an mp3 player by its specs... i had my eye on the MSI Megastick 256mb, but a review said it has useless earphones marked at 20mW... then some *great sound quality* iRivers had 12mW per L + R... then those sony plug-in-to-your-ear earphones were rated at max of 100mW... im getting confused... any1 clarify how to tell good quality from specs and what the mW actually do?