Where is the amplifier in a radio?

i am making a little something something and i need an amp to have more power 2 the speakers becos its running music from the phone and i need more power cos yu cant really hear the music well yu can itz juz not loud enough yu can feel the b from speaker when yu put yur finger in it but yu cant really here it go thats why ( this is what i have done so far ) http://www.youtube.com/watch?v=Mtsy4qV4KPA