How many watts is a powerful amplifier?

Could you please clarify what you mean by a "powerful amplifier"? Amplifiers come in various sizes and capabilities, with wattage ranging from a few watts to thousands of watts. A powerful amplifier could be one that's used for large concerts or events, where it needs to drive large speakers and produce loud, clear sound. These amplifiers can often handle several thousand watts of power. However, for home use or smaller venues, a more modest amplifier with a lower wattage might be sufficient. Could you provide more context about what type of amplifier you're interested in, and what you're using it for?