I do a bit of sound.

The most popular size Yamaha separate power amps are probably the 2 kilowatt ones.

I carry 4 kilowatts for a small room, 8 kilowatts for a larger one.

Wembley stadium, I'd probaby want about 100k. Five years ago, 30k.

It's the bass. Modern bass is going down well below 20Hz, and to make that convincing you need lots and lots of power. 30 years ago I ran a mobile disco with only 200 watts, but it would have been unthinkable to get the "smack" of modern bass. We thought we were doing well if we could get a scalp massage by sticking our heads up to the bass drivers, then. Now, the test is whether you can make your balls rattle (or young ladies express interest at a 30hz sine wave) at 20 paces.