As far as not hearing the dialogue,turn up the centre channel,and you can turn down the surrounds as well.Some receivers have a dynamic range adjustment so you can alter the level of sound effects.It's good to have ample wattage for the times when you do want dynamics,say 80 watts per channel.The amp will hold this in reserve until it's called upon for sound tracks that are demanding at times.If you don't have enough power it puts a strain on the amp which can effect sound quaility or worse case senario,the amp will clip which could cause damage to the amp or speakers.All else being said,you control the volume.