In professional or hi-end equipment, the goal is to have as flat of a response curve as possible. You don't want to mix some audio and have one of your boxes add its own "touch" to it. Most consumer audio on the other hand adds a little boost in the low frequencies and sometimes in the high. FM radio (at least in the States) does this all the time. The same can be said for TV's. Many manufactuers distorted their TV's so that they look good in a showroom setting. The true goal of any pro or hi-end gear is to perfectly reproduce a signal - not "enhance" it.