Consider the sensitivity rating. Usually it means the SPL level at 1 meter from the speaker when driven by 1 Watt of power. So you only need 1 W to get the 91 db SPL, which is pretty loud.

People who are used to the amps with needle or bar meters are likely to be familiar with this. However, I always thought it was going to be a problem using a number display, because the value changes too fast to see it. The same reason they are not that popular in cars, some cars that have them tend to also have a bar graph display too.