For an efficient speaker, even 30W of power is very loud. In the past, the following conditions lead to the use of a lot of power:
1. speaker that need a lot of current
2. inefficient speaker
3. inefficient amp
For switching amp with large capacitors bank, most of the time you are consuming less than 20W (so 0.5A is all you need), and when more power is need, it is supplied by the capacitor bank. The capacitors bank smooth out the need for more power during loud music passage.