Problem with low sound of sony Xperia z c6602

I am using Xperia Z c6602 and I am quite satisfied with phone, I liked its build quantity and its appearance but Sound is very poor. How it can be increased so that I can enjoy it to a certain extent even without headphones.

Thanks for help in advance.

You can't increase sound of handset, they are not meant to be stand alone speaker system rather you should use them with some home theatre or may be some portable speakers. Music is best enjoyed with headphones or with a high quality music system attached else it is only noise and unclear. You can only feel the soul of music when it is played on right media.