What exactly does bigger sound mean to you?
Louder? Larger sound stage? Bigger images?
There is such a thing as too big, btw. When things become disproportional the mind will work harder setting things to order and listening can become tedious.
Theres also too loud, Btw . Regardless the ease with which the music is being delivered SPL is SPL. Your ears dont care how sweet the sound is and it could wind up being like sitting on the beach during an overcast or partly cloudy day with a steady 10 12 knot breeze you get a bad burn then, but you dont feel the heat doing it.
Later on you will.
The relationship between efficiency and power is predictable. Impedance will play a good part in it too. there are charts online which will define how much power is required for exactly which SPL at a speakers rated eff.
Your room alone will dictate to what degree or just how large a sound youll be able to get away with more than anything else. In this instance Ive found little predetermined info regarding what sized speaker for what sized room but it seems more a coincidental or intuitive aspect than anything else.
EX. Focal grand utopias in a 10x12x8 room probably isnt a very good match . Or a pr of stand mounted two ways in a 30x25x14 room likely isnt going to satisfy . Regardless the amps driving them.
Shoehorning too much squeakerage into a room will congest the sound, too little will lean it out.
Power itself plays a far lesser role than does the room, yet each have significant roles.