The manufacturer is Chinese. The datasheet has no details. People selling it have no reviews.Try the module VMA2015, Output power is up to 6W/15W per channel on 8Ohm load (THD = 10%)
Nobody listens to music with the volume control cranked up too high so the amplifier is clipping its head off with 10% distortion. But it makes the power number appear higher.
Its datasheet does not have any curves to see how much or how little is its power and distortion just before clipping.