You know sound of 6600 is very less ,u can double it by following method…first go to tools —- settings —-& select enchacenment option inthat tere are 3 options ..first insert your headphones into your 6600 phone and then select “”"”loopset”"”"” from enchancement option .now go to ultra mp3 and play any song …see the efect of the sound …its the double the original sound…