Professional Yamaha studio monitor speakers versus various 2.1 systems for computers. Back in the day, they called a V-shaped equalisation curve a "disco smile" because was popular for disco music. It's also rather popular on home HiFi systems, where the Loudness button usually applies such a curve. If your speakers sound kind of like a cardboard box, the button merely makes them sound fuller. If your speakers are actually good, it sounds too aggressive.