You do know watts are only a small part of the equation.
My rig is probably only a 100w amp, but put through a 4x10 & it can shift some air.
Going through PA, you could use my 30w combo & be heard by the band (I know this works as I have done it).
Look at how many decibels the rig can muster, look at the spl, but don't think a 500 watt rig is gonna definitely be louder than a 100w one.