If common sense is used, any size amplifier can be employed. Many factors influence amplifier choice. In an extreme example, one might own an inefficient loudspeaker, have a very large room, and like to listen to pipe organ music at realistic levels. The next listener, with the same speaker, may have a much smaller room, and prefers chamber music at background levels. Here, power requirements might be only one tenth to one-fourth those required in the previous illustration.
Requirements do vary widely.
It is wise to take all factors into account before making a decision regarding the amount of power necessary for your situation.